From a969e903a944f69309ee5cc9e7c7b08310d1151e Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 23 Jul 2008 21:27:04 -0700 Subject: kill generic_file_direct_IO() generic_file_direct_IO is a common helper around the invocation of ->direct_IO. But there's almost nothing shared between the read and write side, so we're better off without this helper. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/filemap.c | 117 ++++++++++++++++++++++++++--------------------------------- 1 file changed, 51 insertions(+), 66 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 65d9d9e2b75..6343f3c841b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -42,9 +42,6 @@ #include -static ssize_t -generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs); /* * Shared mappings implemented 30.11.1994. It's not fully working yet, @@ -1205,8 +1202,11 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, goto out; /* skip atime */ size = i_size_read(inode); if (pos < size) { - retval = generic_file_direct_IO(READ, iocb, - iov, pos, nr_segs); + retval = filemap_write_and_wait(mapping); + if (!retval) { + retval = mapping->a_ops->direct_IO(READ, iocb, + iov, pos, nr_segs); + } if (retval > 0) *ppos = pos + retval; } @@ -2004,11 +2004,55 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, struct address_space *mapping = file->f_mapping; struct inode *inode = mapping->host; ssize_t written; + size_t write_len; + pgoff_t end; if (count != ocount) *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count); - written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs); + /* + * Unmap all mmappings of the file up-front. + * + * This will cause any pte dirty bits to be propagated into the + * pageframes for the subsequent filemap_write_and_wait(). + */ + write_len = iov_length(iov, *nr_segs); + end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT; + if (mapping_mapped(mapping)) + unmap_mapping_range(mapping, pos, write_len, 0); + + written = filemap_write_and_wait(mapping); + if (written) + goto out; + + /* + * After a write we want buffered reads to be sure to go to disk to get + * the new data. We invalidate clean cached page from the region we're + * about to write. We do this *before* the write so that we can return + * -EIO without clobbering -EIOCBQUEUED from ->direct_IO(). + */ + if (mapping->nrpages) { + written = invalidate_inode_pages2_range(mapping, + pos >> PAGE_CACHE_SHIFT, end); + if (written) + goto out; + } + + written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); + + /* + * Finally, try again to invalidate clean pages which might have been + * cached by non-direct readahead, or faulted in by get_user_pages() + * if the source of the write was an mmap'ed region of the file + * we're writing. Either one is a pretty crazy thing to do, + * so we don't support it 100%. If this invalidation + * fails, tough, the write still worked... + */ + if (mapping->nrpages) { + invalidate_inode_pages2_range(mapping, + pos >> PAGE_CACHE_SHIFT, end); + } + if (written > 0) { loff_t end = pos + written; if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) { @@ -2024,6 +2068,7 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov, * i_mutex is held, which protects generic_osync_inode() from * livelocking. AIO O_DIRECT ops attempt to sync metadata here. */ +out: if ((written >= 0 || written == -EIOCBQUEUED) && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) { int err = generic_osync_inode(inode, mapping, OSYNC_METADATA); @@ -2511,66 +2556,6 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, } EXPORT_SYMBOL(generic_file_aio_write); -/* - * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something - * went wrong during pagecache shootdown. - */ -static ssize_t -generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, - loff_t offset, unsigned long nr_segs) -{ - struct file *file = iocb->ki_filp; - struct address_space *mapping = file->f_mapping; - ssize_t retval; - size_t write_len; - pgoff_t end = 0; /* silence gcc */ - - /* - * If it's a write, unmap all mmappings of the file up-front. This - * will cause any pte dirty bits to be propagated into the pageframes - * for the subsequent filemap_write_and_wait(). - */ - if (rw == WRITE) { - write_len = iov_length(iov, nr_segs); - end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT; - if (mapping_mapped(mapping)) - unmap_mapping_range(mapping, offset, write_len, 0); - } - - retval = filemap_write_and_wait(mapping); - if (retval) - goto out; - - /* - * After a write we want buffered reads to be sure to go to disk to get - * the new data. We invalidate clean cached page from the region we're - * about to write. We do this *before* the write so that we can return - * -EIO without clobbering -EIOCBQUEUED from ->direct_IO(). - */ - if (rw == WRITE && mapping->nrpages) { - retval = invalidate_inode_pages2_range(mapping, - offset >> PAGE_CACHE_SHIFT, end); - if (retval) - goto out; - } - - retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs); - - /* - * Finally, try again to invalidate clean pages which might have been - * cached by non-direct readahead, or faulted in by get_user_pages() - * if the source of the write was an mmap'ed region of the file - * we're writing. Either one is a pretty crazy thing to do, - * so we don't support it 100%. If this invalidation - * fails, tough, the write still worked... - */ - if (rw == WRITE && mapping->nrpages) { - invalidate_inode_pages2_range(mapping, offset >> PAGE_CACHE_SHIFT, end); - } -out: - return retval; -} - /** * try_to_release_page() - release old fs-specific metadata on a page * -- cgit v1.2.3-70-g09d2 From 11fa977ecde652ab324dd79c179deb52e82a8df1 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Wed, 23 Jul 2008 21:27:34 -0700 Subject: generic_file_aio_read() cleanups As akpm points out, there's really no need for generic_file_aio_read to make a special case of count 0: just loop through nr_segs doing nothing. And as Harvey Harrison points out, there's no need to reset retval to 0 where it's already 0. Setting count (or ocount) to 0 before calling generic_segment_checks is unnecessary too; but reluctantly I'll leave that removal to someone with a wider range of gcc versions to hand - 4.1.2 and 4.2.1 don't warn about it, but perhaps others do - I forget which are the warniest versions. Signed-off-by: Hugh Dickins Tested-by: Lawrence Greenfield Cc: Christoph Rohland Cc: Badari Pulavarty Cc: Zach Brown Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/filemap.c | 42 +++++++++++++++++++----------------------- 1 file changed, 19 insertions(+), 23 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 6343f3c841b..7675b91f4f6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1197,7 +1197,6 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, mapping = filp->f_mapping; inode = mapping->host; - retval = 0; if (!count) goto out; /* skip atime */ size = i_size_read(inode); @@ -1209,33 +1208,30 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, } if (retval > 0) *ppos = pos + retval; - } - if (likely(retval != 0)) { - file_accessed(filp); - goto out; + if (retval) { + file_accessed(filp); + goto out; + } } } - retval = 0; - if (count) { - for (seg = 0; seg < nr_segs; seg++) { - read_descriptor_t desc; + for (seg = 0; seg < nr_segs; seg++) { + read_descriptor_t desc; - desc.written = 0; - desc.arg.buf = iov[seg].iov_base; - desc.count = iov[seg].iov_len; - if (desc.count == 0) - continue; - desc.error = 0; - do_generic_file_read(filp,ppos,&desc,file_read_actor); - retval += desc.written; - if (desc.error) { - retval = retval ?: desc.error; - break; - } - if (desc.count > 0) - break; + desc.written = 0; + desc.arg.buf = iov[seg].iov_base; + desc.count = iov[seg].iov_len; + if (desc.count == 0) + continue; + desc.error = 0; + do_generic_file_read(filp, ppos, &desc, file_read_actor); + retval += desc.written; + if (desc.error) { + retval = retval ?: desc.error; + break; } + if (desc.count > 0) + break; } out: return retval; -- cgit v1.2.3-70-g09d2 From 3f31fddfa26b7594b44ff2b34f9a04ba409e0f91 Mon Sep 17 00:00:00 2001 From: Mingming Cao Date: Fri, 25 Jul 2008 01:46:22 -0700 Subject: jbd: fix race between free buffer and commit transaction journal_try_to_free_buffers() could race with jbd commit transaction when the later is holding the buffer reference while waiting for the data buffer to flush to disk. If the caller of journal_try_to_free_buffers() request tries hard to release the buffers, it will treat the failure as error and return back to the caller. We have seen the directo IO failed due to this race. Some of the caller of releasepage() also expecting the buffer to be dropped when passed with GFP_KERNEL mask to the releasepage()->journal_try_to_free_buffers(). With this patch, if the caller is passing the __GFP_WAIT and __GFP_FS to indicating this call could wait, in case of try_to_free_buffers() failed, let's waiting for journal_commit_transaction() to finish commit the current committing transaction, then try to free those buffers again. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mingming Cao Reviewed-by: Badari Pulavarty Acked-by: Jan Kara Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/jbd/transaction.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++-- mm/filemap.c | 3 +-- 2 files changed, 56 insertions(+), 4 deletions(-) (limited to 'mm/filemap.c') diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c index 67ff2024c23..8dee3200750 100644 --- a/fs/jbd/transaction.c +++ b/fs/jbd/transaction.c @@ -1648,12 +1648,42 @@ out: return; } +/* + * journal_try_to_free_buffers() could race with journal_commit_transaction() + * The latter might still hold the a count on buffers when inspecting + * them on t_syncdata_list or t_locked_list. + * + * journal_try_to_free_buffers() will call this function to + * wait for the current transaction to finish syncing data buffers, before + * tryinf to free that buffer. + * + * Called with journal->j_state_lock held. + */ +static void journal_wait_for_transaction_sync_data(journal_t *journal) +{ + transaction_t *transaction = NULL; + tid_t tid; + + spin_lock(&journal->j_state_lock); + transaction = journal->j_committing_transaction; + + if (!transaction) { + spin_unlock(&journal->j_state_lock); + return; + } + + tid = transaction->t_tid; + spin_unlock(&journal->j_state_lock); + log_wait_commit(journal, tid); +} /** * int journal_try_to_free_buffers() - try to free page buffers. * @journal: journal for operation * @page: to try and free - * @unused_gfp_mask: unused + * @gfp_mask: we use the mask to detect how hard should we try to release + * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to + * release the buffers. * * * For all the buffers on this page, @@ -1682,9 +1712,11 @@ out: * journal_try_to_free_buffer() is changing its state. But that * cannot happen because we never reallocate freed data as metadata * while the data is part of a transaction. Yes? + * + * Return 0 on failure, 1 on success */ int journal_try_to_free_buffers(journal_t *journal, - struct page *page, gfp_t unused_gfp_mask) + struct page *page, gfp_t gfp_mask) { struct buffer_head *head; struct buffer_head *bh; @@ -1713,7 +1745,28 @@ int journal_try_to_free_buffers(journal_t *journal, if (buffer_jbd(bh)) goto busy; } while ((bh = bh->b_this_page) != head); + ret = try_to_free_buffers(page); + + /* + * There are a number of places where journal_try_to_free_buffers() + * could race with journal_commit_transaction(), the later still + * holds the reference to the buffers to free while processing them. + * try_to_free_buffers() failed to free those buffers. Some of the + * caller of releasepage() request page buffers to be dropped, otherwise + * treat the fail-to-free as errors (such as generic_file_direct_IO()) + * + * So, if the caller of try_to_release_page() wants the synchronous + * behaviour(i.e make sure buffers are dropped upon return), + * let's wait for the current transaction to finish flush of + * dirty data buffers, then try to free those buffers again, + * with the journal locked. + */ + if (ret == 0 && (gfp_mask & __GFP_WAIT) && (gfp_mask & __GFP_FS)) { + journal_wait_for_transaction_sync_data(journal); + ret = try_to_free_buffers(page); + } + busy: return ret; } diff --git a/mm/filemap.c b/mm/filemap.c index 7675b91f4f6..5d4c880d7cd 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2563,9 +2563,8 @@ EXPORT_SYMBOL(generic_file_aio_write); * Otherwise return zero. * * The @gfp_mask argument specifies whether I/O may be performed to release - * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). + * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS). * - * NOTE: @gfp_mask may go away, and this function may become non-blocking. */ int try_to_release_page(struct page *page, gfp_t gfp_mask) { -- cgit v1.2.3-70-g09d2 From 69029cd550284e32de13d6dd2f77b723c8a0e444 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Fri, 25 Jul 2008 01:47:14 -0700 Subject: memcg: remove refcnt from page_cgroup memcg: performance improvements Patch Description 1/5 ... remove refcnt fron page_cgroup patch (shmem handling is fixed) 2/5 ... swapcache handling patch 3/5 ... add helper function for shmem's memory reclaim patch 4/5 ... optimize by likely/unlikely ppatch 5/5 ... remove redundunt check patch (shmem handling is fixed.) Unix bench result. == 2.6.26-rc2-mm1 + memory resource controller Execl Throughput 2915.4 lps (29.6 secs, 3 samples) C Compiler Throughput 1019.3 lpm (60.0 secs, 3 samples) Shell Scripts (1 concurrent) 5796.0 lpm (60.0 secs, 3 samples) Shell Scripts (8 concurrent) 1097.7 lpm (60.0 secs, 3 samples) Shell Scripts (16 concurrent) 565.3 lpm (60.0 secs, 3 samples) File Read 1024 bufsize 2000 maxblocks 1022128.0 KBps (30.0 secs, 3 samples) File Write 1024 bufsize 2000 maxblocks 544057.0 KBps (30.0 secs, 3 samples) File Copy 1024 bufsize 2000 maxblocks 346481.0 KBps (30.0 secs, 3 samples) File Read 256 bufsize 500 maxblocks 319325.0 KBps (30.0 secs, 3 samples) File Write 256 bufsize 500 maxblocks 148788.0 KBps (30.0 secs, 3 samples) File Copy 256 bufsize 500 maxblocks 99051.0 KBps (30.0 secs, 3 samples) File Read 4096 bufsize 8000 maxblocks 2058917.0 KBps (30.0 secs, 3 samples) File Write 4096 bufsize 8000 maxblocks 1606109.0 KBps (30.0 secs, 3 samples) File Copy 4096 bufsize 8000 maxblocks 854789.0 KBps (30.0 secs, 3 samples) Dc: sqrt(2) to 99 decimal places 126145.2 lpm (30.0 secs, 3 samples) INDEX VALUES TEST BASELINE RESULT INDEX Execl Throughput 43.0 2915.4 678.0 File Copy 1024 bufsize 2000 maxblocks 3960.0 346481.0 875.0 File Copy 256 bufsize 500 maxblocks 1655.0 99051.0 598.5 File Copy 4096 bufsize 8000 maxblocks 5800.0 854789.0 1473.8 Shell Scripts (8 concurrent) 6.0 1097.7 1829.5 ========= FINAL SCORE 991.3 == 2.6.26-rc2-mm1 + this set == Execl Throughput 3012.9 lps (29.9 secs, 3 samples) C Compiler Throughput 981.0 lpm (60.0 secs, 3 samples) Shell Scripts (1 concurrent) 5872.0 lpm (60.0 secs, 3 samples) Shell Scripts (8 concurrent) 1120.3 lpm (60.0 secs, 3 samples) Shell Scripts (16 concurrent) 578.0 lpm (60.0 secs, 3 samples) File Read 1024 bufsize 2000 maxblocks 1003993.0 KBps (30.0 secs, 3 samples) File Write 1024 bufsize 2000 maxblocks 550452.0 KBps (30.0 secs, 3 samples) File Copy 1024 bufsize 2000 maxblocks 347159.0 KBps (30.0 secs, 3 samples) File Read 256 bufsize 500 maxblocks 314644.0 KBps (30.0 secs, 3 samples) File Write 256 bufsize 500 maxblocks 151852.0 KBps (30.0 secs, 3 samples) File Copy 256 bufsize 500 maxblocks 101000.0 KBps (30.0 secs, 3 samples) File Read 4096 bufsize 8000 maxblocks 2033256.0 KBps (30.0 secs, 3 samples) File Write 4096 bufsize 8000 maxblocks 1611814.0 KBps (30.0 secs, 3 samples) File Copy 4096 bufsize 8000 maxblocks 847979.0 KBps (30.0 secs, 3 samples) Dc: sqrt(2) to 99 decimal places 128148.7 lpm (30.0 secs, 3 samples) INDEX VALUES TEST BASELINE RESULT INDEX Execl Throughput 43.0 3012.9 700.7 File Copy 1024 bufsize 2000 maxblocks 3960.0 347159.0 876.7 File Copy 256 bufsize 500 maxblocks 1655.0 101000.0 610.3 File Copy 4096 bufsize 8000 maxblocks 5800.0 847979.0 1462.0 Shell Scripts (8 concurrent) 6.0 1120.3 1867.2 ========= FINAL SCORE 1004.6 This patch: Remove refcnt from page_cgroup(). After this, * A page is charged only when !page_mapped() && no page_cgroup is assigned. * Anon page is newly mapped. * File page is added to mapping->tree. * A page is uncharged only when * Anon page is fully unmapped. * File page is removed from LRU. There is no change in behavior from user's view. This patch also removes unnecessary calls in rmap.c which was used only for refcnt mangement. [akpm@linux-foundation.org: fix warning] [hugh@veritas.com: fix shmem_unuse_inode charging] Signed-off-by: KAMEZAWA Hiroyuki Cc: Balbir Singh Cc: "Eric W. Biederman" Cc: Pavel Emelyanov Cc: Li Zefan Cc: Hugh Dickins Cc: YAMAMOTO Takashi Cc: Paul Menage Cc: David Rientjes Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memcontrol.h | 10 ++--- mm/filemap.c | 6 +-- mm/memcontrol.c | 109 ++++++++++++++++++++++++++------------------- mm/migrate.c | 3 +- mm/rmap.c | 14 +----- mm/shmem.c | 35 ++++++++++----- 6 files changed, 97 insertions(+), 80 deletions(-) (limited to 'mm/filemap.c') diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 84ead2aa6f1..b4980b8f048 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -35,6 +35,7 @@ extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm, extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask); extern void mem_cgroup_uncharge_page(struct page *page); +extern void mem_cgroup_uncharge_cache_page(struct page *page); extern void mem_cgroup_move_lists(struct page *page, bool active); extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, struct list_head *dst, @@ -53,7 +54,6 @@ extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); extern int mem_cgroup_prepare_migration(struct page *page, struct page *newpage); extern void mem_cgroup_end_migration(struct page *page); -extern int mem_cgroup_getref(struct page *page); /* * For memory reclaim. @@ -98,6 +98,10 @@ static inline void mem_cgroup_uncharge_page(struct page *page) { } +static inline void mem_cgroup_uncharge_cache_page(struct page *page) +{ +} + static inline void mem_cgroup_move_lists(struct page *page, bool active) { } @@ -123,10 +127,6 @@ static inline void mem_cgroup_end_migration(struct page *page) { } -static inline void mem_cgroup_getref(struct page *page) -{ -} - static inline int mem_cgroup_calc_mapped_ratio(struct mem_cgroup *mem) { return 0; diff --git a/mm/filemap.c b/mm/filemap.c index 5d4c880d7cd..2d3ec1ffc66 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -115,7 +115,7 @@ void __remove_from_page_cache(struct page *page) { struct address_space *mapping = page->mapping; - mem_cgroup_uncharge_page(page); + mem_cgroup_uncharge_cache_page(page); radix_tree_delete(&mapping->page_tree, page->index); page->mapping = NULL; mapping->nrpages--; @@ -474,12 +474,12 @@ int add_to_page_cache(struct page *page, struct address_space *mapping, mapping->nrpages++; __inc_zone_page_state(page, NR_FILE_PAGES); } else - mem_cgroup_uncharge_page(page); + mem_cgroup_uncharge_cache_page(page); write_unlock_irq(&mapping->tree_lock); radix_tree_preload_end(); } else - mem_cgroup_uncharge_page(page); + mem_cgroup_uncharge_cache_page(page); out: return error; } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index da5912b8455..a61706193c3 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -166,7 +166,6 @@ struct page_cgroup { struct list_head lru; /* per cgroup LRU list */ struct page *page; struct mem_cgroup *mem_cgroup; - int ref_cnt; /* cached, mapped, migrating */ int flags; }; #define PAGE_CGROUP_FLAG_CACHE (0x1) /* charged as cache */ @@ -185,6 +184,7 @@ static enum zone_type page_cgroup_zid(struct page_cgroup *pc) enum charge_type { MEM_CGROUP_CHARGE_TYPE_CACHE = 0, MEM_CGROUP_CHARGE_TYPE_MAPPED, + MEM_CGROUP_CHARGE_TYPE_FORCE, /* used by force_empty */ }; /* @@ -552,9 +552,7 @@ retry: */ if (pc) { VM_BUG_ON(pc->page != page); - VM_BUG_ON(pc->ref_cnt <= 0); - - pc->ref_cnt++; + VM_BUG_ON(!pc->mem_cgroup); unlock_page_cgroup(page); goto done; } @@ -570,10 +568,7 @@ retry: * thread group leader migrates. It's possible that mm is not * set, if so charge the init_mm (happens for pagecache usage). */ - if (!memcg) { - if (!mm) - mm = &init_mm; - + if (likely(!memcg)) { rcu_read_lock(); mem = mem_cgroup_from_task(rcu_dereference(mm->owner)); /* @@ -609,7 +604,6 @@ retry: } } - pc->ref_cnt = 1; pc->mem_cgroup = mem; pc->page = page; /* @@ -653,6 +647,17 @@ err: int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) { + /* + * If already mapped, we don't have to account. + * If page cache, page->mapping has address_space. + * But page->mapping may have out-of-use anon_vma pointer, + * detecit it by PageAnon() check. newly-mapped-anon's page->mapping + * is NULL. + */ + if (page_mapped(page) || (page->mapping && !PageAnon(page))) + return 0; + if (unlikely(!mm)) + mm = &init_mm; return mem_cgroup_charge_common(page, mm, gfp_mask, MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL); } @@ -660,32 +665,17 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) { - if (!mm) + if (unlikely(!mm)) mm = &init_mm; return mem_cgroup_charge_common(page, mm, gfp_mask, MEM_CGROUP_CHARGE_TYPE_CACHE, NULL); } -int mem_cgroup_getref(struct page *page) -{ - struct page_cgroup *pc; - - if (mem_cgroup_subsys.disabled) - return 0; - - lock_page_cgroup(page); - pc = page_get_page_cgroup(page); - VM_BUG_ON(!pc); - pc->ref_cnt++; - unlock_page_cgroup(page); - return 0; -} - /* - * Uncharging is always a welcome operation, we never complain, simply - * uncharge. + * uncharge if !page_mapped(page) */ -void mem_cgroup_uncharge_page(struct page *page) +static void +__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) { struct page_cgroup *pc; struct mem_cgroup *mem; @@ -704,29 +694,41 @@ void mem_cgroup_uncharge_page(struct page *page) goto unlock; VM_BUG_ON(pc->page != page); - VM_BUG_ON(pc->ref_cnt <= 0); - if (--(pc->ref_cnt) == 0) { - mz = page_cgroup_zoneinfo(pc); - spin_lock_irqsave(&mz->lru_lock, flags); - __mem_cgroup_remove_list(mz, pc); - spin_unlock_irqrestore(&mz->lru_lock, flags); + if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED) + && ((pc->flags & PAGE_CGROUP_FLAG_CACHE) + || page_mapped(page))) + goto unlock; - page_assign_page_cgroup(page, NULL); - unlock_page_cgroup(page); + mz = page_cgroup_zoneinfo(pc); + spin_lock_irqsave(&mz->lru_lock, flags); + __mem_cgroup_remove_list(mz, pc); + spin_unlock_irqrestore(&mz->lru_lock, flags); - mem = pc->mem_cgroup; - res_counter_uncharge(&mem->res, PAGE_SIZE); - css_put(&mem->css); + page_assign_page_cgroup(page, NULL); + unlock_page_cgroup(page); - kmem_cache_free(page_cgroup_cache, pc); - return; - } + mem = pc->mem_cgroup; + res_counter_uncharge(&mem->res, PAGE_SIZE); + css_put(&mem->css); + kmem_cache_free(page_cgroup_cache, pc); + return; unlock: unlock_page_cgroup(page); } +void mem_cgroup_uncharge_page(struct page *page) +{ + __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED); +} + +void mem_cgroup_uncharge_cache_page(struct page *page) +{ + VM_BUG_ON(page_mapped(page)); + __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE); +} + /* * Before starting migration, account against new page. */ @@ -757,15 +759,29 @@ int mem_cgroup_prepare_migration(struct page *page, struct page *newpage) return ret; } -/* remove redundant charge */ +/* remove redundant charge if migration failed*/ void mem_cgroup_end_migration(struct page *newpage) { - mem_cgroup_uncharge_page(newpage); + /* + * At success, page->mapping is not NULL. + * special rollback care is necessary when + * 1. at migration failure. (newpage->mapping is cleared in this case) + * 2. the newpage was moved but not remapped again because the task + * exits and the newpage is obsolete. In this case, the new page + * may be a swapcache. So, we just call mem_cgroup_uncharge_page() + * always for avoiding mess. The page_cgroup will be removed if + * unnecessary. File cache pages is still on radix-tree. Don't + * care it. + */ + if (!newpage->mapping) + __mem_cgroup_uncharge_common(newpage, + MEM_CGROUP_CHARGE_TYPE_FORCE); + else if (PageAnon(newpage)) + mem_cgroup_uncharge_page(newpage); } /* * This routine traverse page_cgroup in given list and drop them all. - * This routine ignores page_cgroup->ref_cnt. * *And* this routine doesn't reclaim page itself, just removes page_cgroup. */ #define FORCE_UNCHARGE_BATCH (128) @@ -795,7 +811,8 @@ static void mem_cgroup_force_empty_list(struct mem_cgroup *mem, * if it's under page migration. */ if (PageLRU(page)) { - mem_cgroup_uncharge_page(page); + __mem_cgroup_uncharge_common(page, + MEM_CGROUP_CHARGE_TYPE_FORCE); put_page(page); if (--count <= 0) { count = FORCE_UNCHARGE_BATCH; diff --git a/mm/migrate.c b/mm/migrate.c index f6d7f8efd1a..d8c65a65c61 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -359,8 +359,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, write_unlock_irq(&mapping->tree_lock); if (!PageSwapCache(newpage)) { - mem_cgroup_uncharge_page(page); - mem_cgroup_getref(newpage); + mem_cgroup_uncharge_cache_page(page); } return 0; diff --git a/mm/rmap.c b/mm/rmap.c index bf0a5b7cfb8..abbd29f7c43 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -576,14 +576,8 @@ void page_add_anon_rmap(struct page *page, VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); if (atomic_inc_and_test(&page->_mapcount)) __page_set_anon_rmap(page, vma, address); - else { + else __page_check_anon_rmap(page, vma, address); - /* - * We unconditionally charged during prepare, we uncharge here - * This takes care of balancing the reference counts - */ - mem_cgroup_uncharge_page(page); - } } /** @@ -614,12 +608,6 @@ void page_add_file_rmap(struct page *page) { if (atomic_inc_and_test(&page->_mapcount)) __inc_zone_page_state(page, NR_FILE_MAPPED); - else - /* - * We unconditionally charged during prepare, we uncharge here - * This takes care of balancing the reference counts - */ - mem_cgroup_uncharge_page(page); } #ifdef CONFIG_DEBUG_VM diff --git a/mm/shmem.c b/mm/shmem.c index 9ffbea9b79e..d58305e8a48 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -922,20 +922,26 @@ found: error = 1; if (!inode) goto out; - /* Precharge page while we can wait, compensate afterwards */ + /* Precharge page using GFP_KERNEL while we can wait */ error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); if (error) goto out; error = radix_tree_preload(GFP_KERNEL); - if (error) - goto uncharge; + if (error) { + mem_cgroup_uncharge_cache_page(page); + goto out; + } error = 1; spin_lock(&info->lock); ptr = shmem_swp_entry(info, idx, NULL); - if (ptr && ptr->val == entry.val) + if (ptr && ptr->val == entry.val) { error = add_to_page_cache(page, inode->i_mapping, idx, GFP_NOWAIT); + /* does mem_cgroup_uncharge_cache_page on error */ + } else /* we must compensate for our precharge above */ + mem_cgroup_uncharge_cache_page(page); + if (error == -EEXIST) { struct page *filepage = find_get_page(inode->i_mapping, idx); error = 1; @@ -961,8 +967,6 @@ found: shmem_swp_unmap(ptr); spin_unlock(&info->lock); radix_tree_preload_end(); -uncharge: - mem_cgroup_uncharge_page(page); out: unlock_page(page); page_cache_release(page); @@ -1319,7 +1323,7 @@ repeat: page_cache_release(swappage); goto failed; } - mem_cgroup_uncharge_page(swappage); + mem_cgroup_uncharge_cache_page(swappage); } page_cache_release(swappage); goto repeat; @@ -1358,6 +1362,8 @@ repeat: } if (!filepage) { + int ret; + spin_unlock(&info->lock); filepage = shmem_alloc_page(gfp, info, idx); if (!filepage) { @@ -1386,10 +1392,18 @@ repeat: swap = *entry; shmem_swp_unmap(entry); } - if (error || swap.val || 0 != add_to_page_cache_lru( - filepage, mapping, idx, GFP_NOWAIT)) { + ret = error || swap.val; + if (ret) + mem_cgroup_uncharge_cache_page(filepage); + else + ret = add_to_page_cache_lru(filepage, mapping, + idx, GFP_NOWAIT); + /* + * At add_to_page_cache_lru() failure, uncharge will + * be done automatically. + */ + if (ret) { spin_unlock(&info->lock); - mem_cgroup_uncharge_page(filepage); page_cache_release(filepage); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); @@ -1398,7 +1412,6 @@ repeat: goto failed; goto repeat; } - mem_cgroup_uncharge_page(filepage); info->flags |= SHMEM_PAGEIN; } -- cgit v1.2.3-70-g09d2 From e286781d5f2e9c846e012a39653a166e9d31777d Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 25 Jul 2008 19:45:30 -0700 Subject: mm: speculative page references If we can be sure that elevating the page_count on a pagecache page will pin it, we can speculatively run this operation, and subsequently check to see if we hit the right page rather than relying on holding a lock or otherwise pinning a reference to the page. This can be done if get_page/put_page behaves consistently throughout the whole tree (ie. if we "get" the page after it has been used for something else, we must be able to free it with a put_page). Actually, there is a period where the count behaves differently: when the page is free or if it is a constituent page of a compound page. We need an atomic_inc_not_zero operation to ensure we don't try to grab the page in either case. This patch introduces the core locking protocol to the pagecache (ie. adds page_cache_get_speculative, and tweaks some update-side code to make it work). Thanks to Hugh for pointing out an improvement to the algorithm setting page_count to zero when we have control of all references, in order to hold off speculative getters. [kamezawa.hiroyu@jp.fujitsu.com: fix migration_entry_wait()] [hugh@veritas.com: fix add_to_page_cache] [akpm@linux-foundation.org: repair a comment] Signed-off-by: Nick Piggin Cc: Jeff Garzik Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Hugh Dickins Cc: "Paul E. McKenney" Reviewed-by: Peter Zijlstra Signed-off-by: Daisuke Nishimura Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: KOSAKI Motohiro Signed-off-by: Hugh Dickins Acked-by: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/net/cassini.c | 12 ++++++ include/linux/pagemap.h | 111 +++++++++++++++++++++++++++++++++++++++++++++++- mm/filemap.c | 32 ++++++++------ mm/migrate.c | 20 ++++++++- mm/shmem.c | 6 +-- mm/swap_state.c | 17 +++++--- mm/vmscan.c | 74 +++++++++++++++++++++++--------- 7 files changed, 227 insertions(+), 45 deletions(-) (limited to 'mm/filemap.c') diff --git a/drivers/net/cassini.c b/drivers/net/cassini.c index 83768df2780..f1936d51b45 100644 --- a/drivers/net/cassini.c +++ b/drivers/net/cassini.c @@ -576,6 +576,18 @@ static void cas_spare_recover(struct cas *cp, const gfp_t flags) list_for_each_safe(elem, tmp, &list) { cas_page_t *page = list_entry(elem, cas_page_t, list); + /* + * With the lockless pagecache, cassini buffering scheme gets + * slightly less accurate: we might find that a page has an + * elevated reference count here, due to a speculative ref, + * and skip it as in-use. Ideally we would be able to reclaim + * it. However this would be such a rare case, it doesn't + * matter too much as we should pick it up the next time round. + * + * Importantly, if we find that the page has a refcount of 1 + * here (our refcount), then we know it is definitely not inuse + * so we can reuse it. + */ if (page_count(page->buffer) > 1) continue; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index ee1ec2c7723..a81d8189042 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -12,6 +12,7 @@ #include #include #include +#include /* for in_interrupt() */ /* * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page @@ -62,6 +63,98 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) #define page_cache_release(page) put_page(page) void release_pages(struct page **pages, int nr, int cold); +/* + * speculatively take a reference to a page. + * If the page is free (_count == 0), then _count is untouched, and 0 + * is returned. Otherwise, _count is incremented by 1 and 1 is returned. + * + * This function must be called inside the same rcu_read_lock() section as has + * been used to lookup the page in the pagecache radix-tree (or page table): + * this allows allocators to use a synchronize_rcu() to stabilize _count. + * + * Unless an RCU grace period has passed, the count of all pages coming out + * of the allocator must be considered unstable. page_count may return higher + * than expected, and put_page must be able to do the right thing when the + * page has been finished with, no matter what it is subsequently allocated + * for (because put_page is what is used here to drop an invalid speculative + * reference). + * + * This is the interesting part of the lockless pagecache (and lockless + * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) + * has the following pattern: + * 1. find page in radix tree + * 2. conditionally increment refcount + * 3. check the page is still in pagecache (if no, goto 1) + * + * Remove-side that cares about stability of _count (eg. reclaim) has the + * following (with tree_lock held for write): + * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) + * B. remove page from pagecache + * C. free the page + * + * There are 2 critical interleavings that matter: + * - 2 runs before A: in this case, A sees elevated refcount and bails out + * - A runs before 2: in this case, 2 sees zero refcount and retries; + * subsequently, B will complete and 1 will find no page, causing the + * lookup to return NULL. + * + * It is possible that between 1 and 2, the page is removed then the exact same + * page is inserted into the same position in pagecache. That's OK: the + * old find_get_page using tree_lock could equally have run before or after + * such a re-insertion, depending on order that locks are granted. + * + * Lookups racing against pagecache insertion isn't a big problem: either 1 + * will find the page or it will not. Likewise, the old find_get_page could run + * either before the insertion or afterwards, depending on timing. + */ +static inline int page_cache_get_speculative(struct page *page) +{ + VM_BUG_ON(in_interrupt()); + +#if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU) +# ifdef CONFIG_PREEMPT + VM_BUG_ON(!in_atomic()); +# endif + /* + * Preempt must be disabled here - we rely on rcu_read_lock doing + * this for us. + * + * Pagecache won't be truncated from interrupt context, so if we have + * found a page in the radix tree here, we have pinned its refcount by + * disabling preempt, and hence no need for the "speculative get" that + * SMP requires. + */ + VM_BUG_ON(page_count(page) == 0); + atomic_inc(&page->_count); + +#else + if (unlikely(!get_page_unless_zero(page))) { + /* + * Either the page has been freed, or will be freed. + * In either case, retry here and the caller should + * do the right thing (see comments above). + */ + return 0; + } +#endif + VM_BUG_ON(PageTail(page)); + + return 1; +} + +static inline int page_freeze_refs(struct page *page, int count) +{ + return likely(atomic_cmpxchg(&page->_count, count, 0) == count); +} + +static inline void page_unfreeze_refs(struct page *page, int count) +{ + VM_BUG_ON(page_count(page) != 0); + VM_BUG_ON(count == 0); + + atomic_set(&page->_count, count); +} + #ifdef CONFIG_NUMA extern struct page *__page_cache_alloc(gfp_t gfp); #else @@ -133,13 +226,29 @@ static inline struct page *read_mapping_page(struct address_space *mapping, return read_cache_page(mapping, index, filler, data); } -int add_to_page_cache(struct page *page, struct address_space *mapping, +int add_to_page_cache_locked(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); int add_to_page_cache_lru(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); extern void remove_from_page_cache(struct page *page); extern void __remove_from_page_cache(struct page *page); +/* + * Like add_to_page_cache_locked, but used to add newly allocated pages: + * the page is new, so we can just run SetPageLocked() against it. + */ +static inline int add_to_page_cache(struct page *page, + struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) +{ + int error; + + SetPageLocked(page); + error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); + if (unlikely(error)) + ClearPageLocked(page); + return error; +} + /* * Return byte-offset into filesystem object for page. */ diff --git a/mm/filemap.c b/mm/filemap.c index 2d3ec1ffc66..4e182a9a14c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -442,39 +442,43 @@ int filemap_write_and_wait_range(struct address_space *mapping, } /** - * add_to_page_cache - add newly allocated pagecache pages + * add_to_page_cache_locked - add a locked page to the pagecache * @page: page to add * @mapping: the page's address_space * @offset: page index * @gfp_mask: page allocation mode * - * This function is used to add newly allocated pagecache pages; - * the page is new, so we can just run SetPageLocked() against it. - * The other page state flags were set by rmqueue(). - * + * This function is used to add a page to the pagecache. It must be locked. * This function does not add the page to the LRU. The caller must do that. */ -int add_to_page_cache(struct page *page, struct address_space *mapping, +int add_to_page_cache_locked(struct page *page, struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) { - int error = mem_cgroup_cache_charge(page, current->mm, + int error; + + VM_BUG_ON(!PageLocked(page)); + + error = mem_cgroup_cache_charge(page, current->mm, gfp_mask & ~__GFP_HIGHMEM); if (error) goto out; error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); if (error == 0) { + page_cache_get(page); + page->mapping = mapping; + page->index = offset; + write_lock_irq(&mapping->tree_lock); error = radix_tree_insert(&mapping->page_tree, offset, page); - if (!error) { - page_cache_get(page); - SetPageLocked(page); - page->mapping = mapping; - page->index = offset; + if (likely(!error)) { mapping->nrpages++; __inc_zone_page_state(page, NR_FILE_PAGES); - } else + } else { + page->mapping = NULL; mem_cgroup_uncharge_cache_page(page); + page_cache_release(page); + } write_unlock_irq(&mapping->tree_lock); radix_tree_preload_end(); @@ -483,7 +487,7 @@ int add_to_page_cache(struct page *page, struct address_space *mapping, out: return error; } -EXPORT_SYMBOL(add_to_page_cache); +EXPORT_SYMBOL(add_to_page_cache_locked); int add_to_page_cache_lru(struct page *page, struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) diff --git a/mm/migrate.c b/mm/migrate.c index d8c65a65c61..3ca6392e82c 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -285,7 +285,15 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, page = migration_entry_to_page(entry); - get_page(page); + /* + * Once radix-tree replacement of page migration started, page_count + * *must* be zero. And, we don't want to call wait_on_page_locked() + * against a page without get_page(). + * So, we use get_page_unless_zero(), here. Even failed, page fault + * will occur again. + */ + if (!get_page_unless_zero(page)) + goto out; pte_unmap_unlock(ptep, ptl); wait_on_page_locked(page); put_page(page); @@ -305,6 +313,7 @@ out: static int migrate_page_move_mapping(struct address_space *mapping, struct page *newpage, struct page *page) { + int expected_count; void **pslot; if (!mapping) { @@ -319,12 +328,18 @@ static int migrate_page_move_mapping(struct address_space *mapping, pslot = radix_tree_lookup_slot(&mapping->page_tree, page_index(page)); - if (page_count(page) != 2 + !!PagePrivate(page) || + expected_count = 2 + !!PagePrivate(page); + if (page_count(page) != expected_count || (struct page *)radix_tree_deref_slot(pslot) != page) { write_unlock_irq(&mapping->tree_lock); return -EAGAIN; } + if (!page_freeze_refs(page, expected_count)) { + write_unlock_irq(&mapping->tree_lock); + return -EAGAIN; + } + /* * Now we know that no one else is looking at the page. */ @@ -338,6 +353,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, radix_tree_replace_slot(pslot, newpage); + page_unfreeze_refs(page, expected_count); /* * Drop cache reference from old page. * We know this isn't the last reference. diff --git a/mm/shmem.c b/mm/shmem.c index f92fea94d03..1089092aeca 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -936,7 +936,7 @@ found: spin_lock(&info->lock); ptr = shmem_swp_entry(info, idx, NULL); if (ptr && ptr->val == entry.val) { - error = add_to_page_cache(page, inode->i_mapping, + error = add_to_page_cache_locked(page, inode->i_mapping, idx, GFP_NOWAIT); /* does mem_cgroup_uncharge_cache_page on error */ } else /* we must compensate for our precharge above */ @@ -1301,8 +1301,8 @@ repeat: SetPageUptodate(filepage); set_page_dirty(filepage); swap_free(swap); - } else if (!(error = add_to_page_cache( - swappage, mapping, idx, GFP_NOWAIT))) { + } else if (!(error = add_to_page_cache_locked(swappage, mapping, + idx, GFP_NOWAIT))) { info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, entry, 0); shmem_swp_unmap(entry); diff --git a/mm/swap_state.c b/mm/swap_state.c index d8aadaf2a0b..3e3381d6c7e 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -64,7 +64,7 @@ void show_swap_cache_info(void) } /* - * add_to_swap_cache resembles add_to_page_cache on swapper_space, + * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space, * but sets SwapCache flag and private instead of mapping and index. */ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) @@ -76,19 +76,26 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) BUG_ON(PagePrivate(page)); error = radix_tree_preload(gfp_mask); if (!error) { + page_cache_get(page); + SetPageSwapCache(page); + set_page_private(page, entry.val); + write_lock_irq(&swapper_space.tree_lock); error = radix_tree_insert(&swapper_space.page_tree, entry.val, page); - if (!error) { - page_cache_get(page); - SetPageSwapCache(page); - set_page_private(page, entry.val); + if (likely(!error)) { total_swapcache_pages++; __inc_zone_page_state(page, NR_FILE_PAGES); INC_CACHE_INFO(add_total); } write_unlock_irq(&swapper_space.tree_lock); radix_tree_preload_end(); + + if (unlikely(error)) { + set_page_private(page, 0UL); + ClearPageSwapCache(page); + page_cache_release(page); + } } return error; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 26672c6cd3c..0075eac1cd0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -391,12 +391,10 @@ static pageout_t pageout(struct page *page, struct address_space *mapping, } /* - * Attempt to detach a locked page from its ->mapping. If it is dirty or if - * someone else has a ref on the page, abort and return 0. If it was - * successfully detached, return 1. Assumes the caller has a single ref on - * this page. + * Same as remove_mapping, but if the page is removed from the mapping, it + * gets returned with a refcount of 0. */ -int remove_mapping(struct address_space *mapping, struct page *page) +static int __remove_mapping(struct address_space *mapping, struct page *page) { BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); @@ -427,24 +425,24 @@ int remove_mapping(struct address_space *mapping, struct page *page) * Note that if SetPageDirty is always performed via set_page_dirty, * and thus under tree_lock, then this ordering is not required. */ - if (unlikely(page_count(page) != 2)) + if (!page_freeze_refs(page, 2)) goto cannot_free; - smp_rmb(); - if (unlikely(PageDirty(page))) + /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ + if (unlikely(PageDirty(page))) { + page_unfreeze_refs(page, 2); goto cannot_free; + } if (PageSwapCache(page)) { swp_entry_t swap = { .val = page_private(page) }; __delete_from_swap_cache(page); write_unlock_irq(&mapping->tree_lock); swap_free(swap); - __put_page(page); /* The pagecache ref */ - return 1; + } else { + __remove_from_page_cache(page); + write_unlock_irq(&mapping->tree_lock); } - __remove_from_page_cache(page); - write_unlock_irq(&mapping->tree_lock); - __put_page(page); return 1; cannot_free: @@ -452,6 +450,26 @@ cannot_free: return 0; } +/* + * Attempt to detach a locked page from its ->mapping. If it is dirty or if + * someone else has a ref on the page, abort and return 0. If it was + * successfully detached, return 1. Assumes the caller has a single ref on + * this page. + */ +int remove_mapping(struct address_space *mapping, struct page *page) +{ + if (__remove_mapping(mapping, page)) { + /* + * Unfreezing the refcount with 1 rather than 2 effectively + * drops the pagecache ref for us without requiring another + * atomic operation. + */ + page_unfreeze_refs(page, 1); + return 1; + } + return 0; +} + /* * shrink_page_list() returns the number of reclaimed pages */ @@ -598,18 +616,34 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (PagePrivate(page)) { if (!try_to_release_page(page, sc->gfp_mask)) goto activate_locked; - if (!mapping && page_count(page) == 1) - goto free_it; + if (!mapping && page_count(page) == 1) { + unlock_page(page); + if (put_page_testzero(page)) + goto free_it; + else { + /* + * rare race with speculative reference. + * the speculative reference will free + * this page shortly, so we may + * increment nr_reclaimed here (and + * leave it off the LRU). + */ + nr_reclaimed++; + continue; + } + } } - if (!mapping || !remove_mapping(mapping, page)) + if (!mapping || !__remove_mapping(mapping, page)) goto keep_locked; -free_it: unlock_page(page); +free_it: nr_reclaimed++; - if (!pagevec_add(&freed_pvec, page)) - __pagevec_release_nonlru(&freed_pvec); + if (!pagevec_add(&freed_pvec, page)) { + __pagevec_free(&freed_pvec); + pagevec_reinit(&freed_pvec); + } continue; activate_locked: @@ -623,7 +657,7 @@ keep: } list_splice(&ret_pages, page_list); if (pagevec_count(&freed_pvec)) - __pagevec_release_nonlru(&freed_pvec); + __pagevec_free(&freed_pvec); count_vm_events(PGACTIVATE, pgactivate); return nr_reclaimed; } -- cgit v1.2.3-70-g09d2 From a60637c85893e7191faaafa6a72e197c24386727 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 25 Jul 2008 19:45:31 -0700 Subject: mm: lockless pagecache Combine page_cache_get_speculative with lockless radix tree lookups to introduce lockless page cache lookups (ie. no mapping->tree_lock on the read-side). The only atomicity changes this introduces is that the gang pagecache lookup functions now behave as if they are implemented with multiple find_get_page calls, rather than operating on a snapshot of the pages. In practice, this atomicity guarantee is not used anyway, and it is to replace individual lookups, so these semantics are natural. Signed-off-by: Nick Piggin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Hugh Dickins Cc: "Paul E. McKenney" Reviewed-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/filemap.c | 179 ++++++++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 134 insertions(+), 45 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 4e182a9a14c..feb8448d861 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -637,15 +637,35 @@ void __lock_page_nosync(struct page *page) * Is there a pagecache struct page at the given (mapping, offset) tuple? * If yes, increment its refcount and return it; if no, return NULL. */ -struct page * find_get_page(struct address_space *mapping, pgoff_t offset) +struct page *find_get_page(struct address_space *mapping, pgoff_t offset) { + void **pagep; struct page *page; - read_lock_irq(&mapping->tree_lock); - page = radix_tree_lookup(&mapping->page_tree, offset); - if (page) - page_cache_get(page); - read_unlock_irq(&mapping->tree_lock); + rcu_read_lock(); +repeat: + page = NULL; + pagep = radix_tree_lookup_slot(&mapping->page_tree, offset); + if (pagep) { + page = radix_tree_deref_slot(pagep); + if (unlikely(!page || page == RADIX_TREE_RETRY)) + goto repeat; + + if (!page_cache_get_speculative(page)) + goto repeat; + + /* + * Has the page moved? + * This is part of the lockless pagecache protocol. See + * include/linux/pagemap.h for details. + */ + if (unlikely(page != *pagep)) { + page_cache_release(page); + goto repeat; + } + } + rcu_read_unlock(); + return page; } EXPORT_SYMBOL(find_get_page); @@ -660,32 +680,22 @@ EXPORT_SYMBOL(find_get_page); * * Returns zero if the page was not present. find_lock_page() may sleep. */ -struct page *find_lock_page(struct address_space *mapping, - pgoff_t offset) +struct page *find_lock_page(struct address_space *mapping, pgoff_t offset) { struct page *page; repeat: - read_lock_irq(&mapping->tree_lock); - page = radix_tree_lookup(&mapping->page_tree, offset); + page = find_get_page(mapping, offset); if (page) { - page_cache_get(page); - if (TestSetPageLocked(page)) { - read_unlock_irq(&mapping->tree_lock); - __lock_page(page); - - /* Has the page been truncated while we slept? */ - if (unlikely(page->mapping != mapping)) { - unlock_page(page); - page_cache_release(page); - goto repeat; - } - VM_BUG_ON(page->index != offset); - goto out; + lock_page(page); + /* Has the page been truncated? */ + if (unlikely(page->mapping != mapping)) { + unlock_page(page); + page_cache_release(page); + goto repeat; } + VM_BUG_ON(page->index != offset); } - read_unlock_irq(&mapping->tree_lock); -out: return page; } EXPORT_SYMBOL(find_lock_page); @@ -751,13 +761,39 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start, { unsigned int i; unsigned int ret; + unsigned int nr_found; + + rcu_read_lock(); +restart: + nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, + (void ***)pages, start, nr_pages); + ret = 0; + for (i = 0; i < nr_found; i++) { + struct page *page; +repeat: + page = radix_tree_deref_slot((void **)pages[i]); + if (unlikely(!page)) + continue; + /* + * this can only trigger if nr_found == 1, making livelock + * a non issue. + */ + if (unlikely(page == RADIX_TREE_RETRY)) + goto restart; + + if (!page_cache_get_speculative(page)) + goto repeat; - read_lock_irq(&mapping->tree_lock); - ret = radix_tree_gang_lookup(&mapping->page_tree, - (void **)pages, start, nr_pages); - for (i = 0; i < ret; i++) - page_cache_get(pages[i]); - read_unlock_irq(&mapping->tree_lock); + /* Has the page moved? */ + if (unlikely(page != *((void **)pages[i]))) { + page_cache_release(page); + goto repeat; + } + + pages[ret] = page; + ret++; + } + rcu_read_unlock(); return ret; } @@ -778,19 +814,44 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index, { unsigned int i; unsigned int ret; + unsigned int nr_found; + + rcu_read_lock(); +restart: + nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, + (void ***)pages, index, nr_pages); + ret = 0; + for (i = 0; i < nr_found; i++) { + struct page *page; +repeat: + page = radix_tree_deref_slot((void **)pages[i]); + if (unlikely(!page)) + continue; + /* + * this can only trigger if nr_found == 1, making livelock + * a non issue. + */ + if (unlikely(page == RADIX_TREE_RETRY)) + goto restart; - read_lock_irq(&mapping->tree_lock); - ret = radix_tree_gang_lookup(&mapping->page_tree, - (void **)pages, index, nr_pages); - for (i = 0; i < ret; i++) { - if (pages[i]->mapping == NULL || pages[i]->index != index) + if (page->mapping == NULL || page->index != index) break; - page_cache_get(pages[i]); + if (!page_cache_get_speculative(page)) + goto repeat; + + /* Has the page moved? */ + if (unlikely(page != *((void **)pages[i]))) { + page_cache_release(page); + goto repeat; + } + + pages[ret] = page; + ret++; index++; } - read_unlock_irq(&mapping->tree_lock); - return i; + rcu_read_unlock(); + return ret; } EXPORT_SYMBOL(find_get_pages_contig); @@ -810,15 +871,43 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, { unsigned int i; unsigned int ret; + unsigned int nr_found; + + rcu_read_lock(); +restart: + nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree, + (void ***)pages, *index, nr_pages, tag); + ret = 0; + for (i = 0; i < nr_found; i++) { + struct page *page; +repeat: + page = radix_tree_deref_slot((void **)pages[i]); + if (unlikely(!page)) + continue; + /* + * this can only trigger if nr_found == 1, making livelock + * a non issue. + */ + if (unlikely(page == RADIX_TREE_RETRY)) + goto restart; + + if (!page_cache_get_speculative(page)) + goto repeat; + + /* Has the page moved? */ + if (unlikely(page != *((void **)pages[i]))) { + page_cache_release(page); + goto repeat; + } + + pages[ret] = page; + ret++; + } + rcu_read_unlock(); - read_lock_irq(&mapping->tree_lock); - ret = radix_tree_gang_lookup_tag(&mapping->page_tree, - (void **)pages, *index, nr_pages, tag); - for (i = 0; i < ret; i++) - page_cache_get(pages[i]); if (ret) *index = pages[ret - 1]->index + 1; - read_unlock_irq(&mapping->tree_lock); + return ret; } EXPORT_SYMBOL(find_get_pages_tag); -- cgit v1.2.3-70-g09d2 From 19fd6231279be3c3bdd02ed99f9b0eb195978064 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 25 Jul 2008 19:45:32 -0700 Subject: mm: spinlock tree_lock mapping->tree_lock has no read lockers. convert the lock from an rwlock to a spinlock. Signed-off-by: Nick Piggin Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Hugh Dickins Cc: "Paul E. McKenney" Reviewed-by: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/buffer.c | 4 ++-- fs/inode.c | 2 +- include/asm-arm/cacheflush.h | 4 ++-- include/asm-parisc/cacheflush.h | 4 ++-- include/linux/fs.h | 2 +- mm/filemap.c | 10 +++++----- mm/migrate.c | 11 +++++------ mm/page-writeback.c | 12 ++++++------ mm/swap_state.c | 10 +++++----- mm/swapfile.c | 4 ++-- mm/truncate.c | 6 +++--- mm/vmscan.c | 8 ++++---- 12 files changed, 38 insertions(+), 39 deletions(-) (limited to 'mm/filemap.c') diff --git a/fs/buffer.c b/fs/buffer.c index d48caee12e2..109b261192d 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -706,7 +706,7 @@ static int __set_page_dirty(struct page *page, if (TestSetPageDirty(page)) return 0; - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); if (page->mapping) { /* Race with truncate? */ WARN_ON_ONCE(warn && !PageUptodate(page)); @@ -719,7 +719,7 @@ static int __set_page_dirty(struct page *page, radix_tree_tag_set(&mapping->page_tree, page_index(page), PAGECACHE_TAG_DIRTY); } - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); return 1; diff --git a/fs/inode.c b/fs/inode.c index c36d9480335..35b6414522e 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -209,7 +209,7 @@ void inode_init_once(struct inode *inode) INIT_LIST_HEAD(&inode->i_dentry); INIT_LIST_HEAD(&inode->i_devices); INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC); - rwlock_init(&inode->i_data.tree_lock); + spin_lock_init(&inode->i_data.tree_lock); spin_lock_init(&inode->i_data.i_mmap_lock); INIT_LIST_HEAD(&inode->i_data.private_list); spin_lock_init(&inode->i_data.private_lock); diff --git a/include/asm-arm/cacheflush.h b/include/asm-arm/cacheflush.h index 70b0fe724b6..03cf1ee977b 100644 --- a/include/asm-arm/cacheflush.h +++ b/include/asm-arm/cacheflush.h @@ -424,9 +424,9 @@ static inline void flush_anon_page(struct vm_area_struct *vma, } #define flush_dcache_mmap_lock(mapping) \ - write_lock_irq(&(mapping)->tree_lock) + spin_lock_irq(&(mapping)->tree_lock) #define flush_dcache_mmap_unlock(mapping) \ - write_unlock_irq(&(mapping)->tree_lock) + spin_unlock_irq(&(mapping)->tree_lock) #define flush_icache_user_range(vma,page,addr,len) \ flush_dcache_page(page) diff --git a/include/asm-parisc/cacheflush.h b/include/asm-parisc/cacheflush.h index 2f1e1b05440..b7ca6dc7fdd 100644 --- a/include/asm-parisc/cacheflush.h +++ b/include/asm-parisc/cacheflush.h @@ -45,9 +45,9 @@ void flush_cache_mm(struct mm_struct *mm); extern void flush_dcache_page(struct page *page); #define flush_dcache_mmap_lock(mapping) \ - write_lock_irq(&(mapping)->tree_lock) + spin_lock_irq(&(mapping)->tree_lock) #define flush_dcache_mmap_unlock(mapping) \ - write_unlock_irq(&(mapping)->tree_lock) + spin_unlock_irq(&(mapping)->tree_lock) #define flush_icache_page(vma,page) do { \ flush_kernel_dcache_page(page); \ diff --git a/include/linux/fs.h b/include/linux/fs.h index 49d8eb7a71b..53d2edb709b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -499,7 +499,7 @@ struct backing_dev_info; struct address_space { struct inode *host; /* owner: inode, block_device */ struct radix_tree_root page_tree; /* radix tree of all pages */ - rwlock_t tree_lock; /* and rwlock protecting it */ + spinlock_t tree_lock; /* and lock protecting it */ unsigned int i_mmap_writable;/* count VM_SHARED mappings */ struct prio_tree_root i_mmap; /* tree of private and shared mappings */ struct list_head i_mmap_nonlinear;/*list VM_NONLINEAR mappings */ diff --git a/mm/filemap.c b/mm/filemap.c index feb8448d861..2ed8b0389c5 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -109,7 +109,7 @@ /* * Remove a page from the page cache and free it. Caller has to make * sure the page is locked and that nobody else uses it - or that usage - * is safe. The caller must hold a write_lock on the mapping's tree_lock. + * is safe. The caller must hold the mapping's tree_lock. */ void __remove_from_page_cache(struct page *page) { @@ -141,9 +141,9 @@ void remove_from_page_cache(struct page *page) BUG_ON(!PageLocked(page)); - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); __remove_from_page_cache(page); - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); } static int sync_page(void *word) @@ -469,7 +469,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, page->mapping = mapping; page->index = offset; - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); error = radix_tree_insert(&mapping->page_tree, offset, page); if (likely(!error)) { mapping->nrpages++; @@ -480,7 +480,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, page_cache_release(page); } - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); radix_tree_preload_end(); } else mem_cgroup_uncharge_cache_page(page); diff --git a/mm/migrate.c b/mm/migrate.c index 3ca6392e82c..153572fb60b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -323,7 +323,7 @@ static int migrate_page_move_mapping(struct address_space *mapping, return 0; } - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); pslot = radix_tree_lookup_slot(&mapping->page_tree, page_index(page)); @@ -331,12 +331,12 @@ static int migrate_page_move_mapping(struct address_space *mapping, expected_count = 2 + !!PagePrivate(page); if (page_count(page) != expected_count || (struct page *)radix_tree_deref_slot(pslot) != page) { - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); return -EAGAIN; } if (!page_freeze_refs(page, expected_count)) { - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); return -EAGAIN; } @@ -373,10 +373,9 @@ static int migrate_page_move_mapping(struct address_space *mapping, __dec_zone_page_state(page, NR_FILE_PAGES); __inc_zone_page_state(newpage, NR_FILE_PAGES); - write_unlock_irq(&mapping->tree_lock); - if (!PageSwapCache(newpage)) { + spin_unlock_irq(&mapping->tree_lock); + if (!PageSwapCache(newpage)) mem_cgroup_uncharge_cache_page(page); - } return 0; } diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 94c6d8988ab..24de8b65fdb 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1088,7 +1088,7 @@ int __set_page_dirty_nobuffers(struct page *page) if (!mapping) return 1; - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); mapping2 = page_mapping(page); if (mapping2) { /* Race with truncate? */ BUG_ON(mapping2 != mapping); @@ -1102,7 +1102,7 @@ int __set_page_dirty_nobuffers(struct page *page) radix_tree_tag_set(&mapping->page_tree, page_index(page), PAGECACHE_TAG_DIRTY); } - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); if (mapping->host) { /* !PageAnon && !swapper_space */ __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); @@ -1258,7 +1258,7 @@ int test_clear_page_writeback(struct page *page) struct backing_dev_info *bdi = mapping->backing_dev_info; unsigned long flags; - write_lock_irqsave(&mapping->tree_lock, flags); + spin_lock_irqsave(&mapping->tree_lock, flags); ret = TestClearPageWriteback(page); if (ret) { radix_tree_tag_clear(&mapping->page_tree, @@ -1269,7 +1269,7 @@ int test_clear_page_writeback(struct page *page) __bdi_writeout_inc(bdi); } } - write_unlock_irqrestore(&mapping->tree_lock, flags); + spin_unlock_irqrestore(&mapping->tree_lock, flags); } else { ret = TestClearPageWriteback(page); } @@ -1287,7 +1287,7 @@ int test_set_page_writeback(struct page *page) struct backing_dev_info *bdi = mapping->backing_dev_info; unsigned long flags; - write_lock_irqsave(&mapping->tree_lock, flags); + spin_lock_irqsave(&mapping->tree_lock, flags); ret = TestSetPageWriteback(page); if (!ret) { radix_tree_tag_set(&mapping->page_tree, @@ -1300,7 +1300,7 @@ int test_set_page_writeback(struct page *page) radix_tree_tag_clear(&mapping->page_tree, page_index(page), PAGECACHE_TAG_DIRTY); - write_unlock_irqrestore(&mapping->tree_lock, flags); + spin_unlock_irqrestore(&mapping->tree_lock, flags); } else { ret = TestSetPageWriteback(page); } diff --git a/mm/swap_state.c b/mm/swap_state.c index 3e3381d6c7e..2c217e33d49 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -39,7 +39,7 @@ static struct backing_dev_info swap_backing_dev_info = { struct address_space swapper_space = { .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN), - .tree_lock = __RW_LOCK_UNLOCKED(swapper_space.tree_lock), + .tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock), .a_ops = &swap_aops, .i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear), .backing_dev_info = &swap_backing_dev_info, @@ -80,7 +80,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) SetPageSwapCache(page); set_page_private(page, entry.val); - write_lock_irq(&swapper_space.tree_lock); + spin_lock_irq(&swapper_space.tree_lock); error = radix_tree_insert(&swapper_space.page_tree, entry.val, page); if (likely(!error)) { @@ -88,7 +88,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) __inc_zone_page_state(page, NR_FILE_PAGES); INC_CACHE_INFO(add_total); } - write_unlock_irq(&swapper_space.tree_lock); + spin_unlock_irq(&swapper_space.tree_lock); radix_tree_preload_end(); if (unlikely(error)) { @@ -182,9 +182,9 @@ void delete_from_swap_cache(struct page *page) entry.val = page_private(page); - write_lock_irq(&swapper_space.tree_lock); + spin_lock_irq(&swapper_space.tree_lock); __delete_from_swap_cache(page); - write_unlock_irq(&swapper_space.tree_lock); + spin_unlock_irq(&swapper_space.tree_lock); swap_free(entry); page_cache_release(page); diff --git a/mm/swapfile.c b/mm/swapfile.c index 2f33edb8bee..af283933c14 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -369,13 +369,13 @@ int remove_exclusive_swap_page(struct page *page) retval = 0; if (p->swap_map[swp_offset(entry)] == 1) { /* Recheck the page count with the swapcache lock held.. */ - write_lock_irq(&swapper_space.tree_lock); + spin_lock_irq(&swapper_space.tree_lock); if ((page_count(page) == 2) && !PageWriteback(page)) { __delete_from_swap_cache(page); SetPageDirty(page); retval = 1; } - write_unlock_irq(&swapper_space.tree_lock); + spin_unlock_irq(&swapper_space.tree_lock); } spin_unlock(&swap_lock); diff --git a/mm/truncate.c b/mm/truncate.c index b8961cb6341..e68443d7456 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -349,18 +349,18 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL)) return 0; - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); if (PageDirty(page)) goto failed; BUG_ON(PagePrivate(page)); __remove_from_page_cache(page); - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); ClearPageUptodate(page); page_cache_release(page); /* pagecache ref */ return 1; failed: - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); return 0; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 0075eac1cd0..8f71761bc4b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -399,7 +399,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page) BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); - write_lock_irq(&mapping->tree_lock); + spin_lock_irq(&mapping->tree_lock); /* * The non racy check for a busy page. * @@ -436,17 +436,17 @@ static int __remove_mapping(struct address_space *mapping, struct page *page) if (PageSwapCache(page)) { swp_entry_t swap = { .val = page_private(page) }; __delete_from_swap_cache(page); - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); swap_free(swap); } else { __remove_from_page_cache(page); - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); } return 1; cannot_free: - write_unlock_irq(&mapping->tree_lock); + spin_unlock_irq(&mapping->tree_lock); return 0; } -- cgit v1.2.3-70-g09d2 From 2f1936b87783a3a56c9441b27b9ba7a747f11e8e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 24 Jun 2008 16:50:14 +0200 Subject: [patch 3/5] vfs: change remove_suid() to file_remove_suid() All calls to remove_suid() are made with a file pointer, because (similarly to file_update_time) it is called when the file is written. Clean up callers by passing in a file instead of a dentry. Signed-off-by: Miklos Szeredi --- fs/fuse/file.c | 2 +- fs/ntfs/file.c | 2 +- fs/splice.c | 4 ++-- fs/xfs/linux-2.6/xfs_lrw.c | 2 +- include/linux/fs.h | 2 +- mm/filemap.c | 7 ++++--- mm/filemap_xip.c | 2 +- 7 files changed, 11 insertions(+), 10 deletions(-) (limited to 'mm/filemap.c') diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 67ff2c6a8f6..2bada6bbc31 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -893,7 +893,7 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov, if (count == 0) goto out; - err = remove_suid(file->f_path.dentry); + err = file_remove_suid(file); if (err) goto out; diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c index 3c5550cd11d..d020866d423 100644 --- a/fs/ntfs/file.c +++ b/fs/ntfs/file.c @@ -2118,7 +2118,7 @@ static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb, goto out; if (!count) goto out; - err = remove_suid(file->f_path.dentry); + err = file_remove_suid(file); if (err) goto out; file_update_time(file); diff --git a/fs/splice.c b/fs/splice.c index 47dc1a445d1..b30311ba8af 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -772,7 +772,7 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, ssize_t ret; int err; - err = remove_suid(out->f_path.dentry); + err = file_remove_suid(out); if (unlikely(err)) return err; @@ -830,7 +830,7 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, ssize_t ret; inode_double_lock(inode, pipe->inode); - ret = remove_suid(out->f_path.dentry); + ret = file_remove_suid(out); if (likely(!ret)) ret = __splice_from_pipe(pipe, &sd, pipe_to_file); inode_double_unlock(inode, pipe->inode); diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c index 5e3b57516ec..82333b3e118 100644 --- a/fs/xfs/linux-2.6/xfs_lrw.c +++ b/fs/xfs/linux-2.6/xfs_lrw.c @@ -711,7 +711,7 @@ start: !capable(CAP_FSETID)) { error = xfs_write_clear_setuid(xip); if (likely(!error)) - error = -remove_suid(file->f_path.dentry); + error = -file_remove_suid(file); if (unlikely(error)) { goto out_unlock_internal; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 6c923c9b79b..1a3546e69f9 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1834,7 +1834,7 @@ extern void clear_inode(struct inode *); extern void destroy_inode(struct inode *); extern struct inode *new_inode(struct super_block *); extern int should_remove_suid(struct dentry *); -extern int remove_suid(struct dentry *); +extern int file_remove_suid(struct file *); extern void __insert_inode_hash(struct inode *, unsigned long hashval); extern void remove_inode_hash(struct inode *); diff --git a/mm/filemap.c b/mm/filemap.c index 2ed8b0389c5..5de7633e1db 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1758,8 +1758,9 @@ static int __remove_suid(struct dentry *dentry, int kill) return notify_change(dentry, &newattrs); } -int remove_suid(struct dentry *dentry) +int file_remove_suid(struct file *file) { + struct dentry *dentry = file->f_path.dentry; int killsuid = should_remove_suid(dentry); int killpriv = security_inode_need_killpriv(dentry); int error = 0; @@ -1773,7 +1774,7 @@ int remove_suid(struct dentry *dentry) return error; } -EXPORT_SYMBOL(remove_suid); +EXPORT_SYMBOL(file_remove_suid); static size_t __iovec_copy_from_user_inatomic(char *vaddr, const struct iovec *iov, size_t base, size_t bytes) @@ -2529,7 +2530,7 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, if (count == 0) goto out; - err = remove_suid(file->f_path.dentry); + err = file_remove_suid(file); if (err) goto out; diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c index 3e744abcce9..98a3f31ccd6 100644 --- a/mm/filemap_xip.c +++ b/mm/filemap_xip.c @@ -380,7 +380,7 @@ xip_file_write(struct file *filp, const char __user *buf, size_t len, if (count == 0) goto out_backing; - ret = remove_suid(filp->f_path.dentry); + ret = file_remove_suid(filp); if (ret) goto out_backing; -- cgit v1.2.3-70-g09d2 From 8ab22b9abb5c55413802e4adc9aa6223324547c3 Mon Sep 17 00:00:00 2001 From: Hisashi Hifumi Date: Mon, 28 Jul 2008 15:46:36 -0700 Subject: vfs: pagecache usage optimization for pagesize!=blocksize When we read some part of a file through pagecache, if there is a pagecache of corresponding index but this page is not uptodate, read IO is issued and this page will be uptodate. I think this is good for pagesize == blocksize environment but there is room for improvement on pagesize != blocksize environment. Because in this case a page can have multiple buffers and even if a page is not uptodate, some buffers can be uptodate. So I suggest that when all buffers which correspond to a part of a file that we want to read are uptodate, use this pagecache and copy data from this pagecache to user buffer even if a page is not uptodate. This can reduce read IO and improve system throughput. I wrote a benchmark program and got result number with this program. This benchmark do: 1: mount and open a test file. 2: create a 512MB file. 3: close a file and umount. 4: mount and again open a test file. 5: pwrite randomly 300000 times on a test file. offset is aligned by IO size(1024bytes). 6: measure time of preading randomly 100000 times on a test file. The result was: 2.6.26 330 sec 2.6.26-patched 226 sec Arch:i386 Filesystem:ext3 Blocksize:1024 bytes Memory: 1GB On ext3/4, a file is written through buffer/block. So random read/write mixed workloads or random read after random write workloads are optimized with this patch under pagesize != blocksize environment. This test result showed this. The benchmark program is as follows: #include #include #include #include #include #include #include #include #include #define LEN 1024 #define LOOP 1024*512 /* 512MB */ main(void) { unsigned long i, offset, filesize; int fd; char buf[LEN]; time_t t1, t2; if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) { perror("cannot mount\n"); exit(1); } memset(buf, 0, LEN); fd = open("/root/test1/testfile", O_CREAT|O_RDWR|O_TRUNC); if (fd < 0) { perror("cannot open file\n"); exit(1); } for (i = 0; i < LOOP; i++) write(fd, buf, LEN); close(fd); if (umount("/root/test1/") < 0) { perror("cannot umount\n"); exit(1); } if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) { perror("cannot mount\n"); exit(1); } fd = open("/root/test1/testfile", O_RDWR); if (fd < 0) { perror("cannot open file\n"); exit(1); } filesize = LEN * LOOP; for (i = 0; i < 300000; i++){ offset = (random() % filesize) & (~(LEN - 1)); pwrite(fd, buf, LEN, offset); } printf("start test\n"); time(&t1); for (i = 0; i < 100000; i++){ offset = (random() % filesize) & (~(LEN - 1)); pread(fd, buf, LEN, offset); } time(&t2); printf("%ld sec\n", t2-t1); close(fd); if (umount("/root/test1/") < 0) { perror("cannot umount\n"); exit(1); } } Signed-off-by: Hisashi Hifumi Cc: Nick Piggin Cc: Christoph Hellwig Cc: Jan Kara Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/buffer.c | 46 +++++++++++++++++++++++ fs/ext2/inode.c | 1 + fs/ext3/inode.c | 67 +++++++++++++++++---------------- fs/ext4/inode.c | 92 +++++++++++++++++++++++---------------------- include/linux/buffer_head.h | 2 + include/linux/fs.h | 44 +++++++++++----------- mm/filemap.c | 14 ++++++- 7 files changed, 167 insertions(+), 99 deletions(-) (limited to 'mm/filemap.c') diff --git a/fs/buffer.c b/fs/buffer.c index f9580501963..ca12a6bb82b 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2095,6 +2095,52 @@ int generic_write_end(struct file *file, struct address_space *mapping, } EXPORT_SYMBOL(generic_write_end); +/* + * block_is_partially_uptodate checks whether buffers within a page are + * uptodate or not. + * + * Returns true if all buffers which correspond to a file portion + * we want to read are uptodate. + */ +int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, + unsigned long from) +{ + struct inode *inode = page->mapping->host; + unsigned block_start, block_end, blocksize; + unsigned to; + struct buffer_head *bh, *head; + int ret = 1; + + if (!page_has_buffers(page)) + return 0; + + blocksize = 1 << inode->i_blkbits; + to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); + to = from + to; + if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) + return 0; + + head = page_buffers(page); + bh = head; + block_start = 0; + do { + block_end = block_start + blocksize; + if (block_end > from && block_start < to) { + if (!buffer_uptodate(bh)) { + ret = 0; + break; + } + if (block_end >= to) + break; + } + block_start = block_end; + bh = bh->b_this_page; + } while (bh != head); + + return ret; +} +EXPORT_SYMBOL(block_is_partially_uptodate); + /* * Generic "read page" function for block devices that have the normal * get_block functionality. This is most of the block device filesystems. diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index 384fc0d1dd7..991d6dfeb51 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -791,6 +791,7 @@ const struct address_space_operations ext2_aops = { .direct_IO = ext2_direct_IO, .writepages = ext2_writepages, .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; const struct address_space_operations ext2_aops_xip = { diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index 3bf07d70b91..507d8689b11 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -1767,44 +1767,47 @@ static int ext3_journalled_set_page_dirty(struct page *page) } static const struct address_space_operations ext3_ordered_aops = { - .readpage = ext3_readpage, - .readpages = ext3_readpages, - .writepage = ext3_ordered_writepage, - .sync_page = block_sync_page, - .write_begin = ext3_write_begin, - .write_end = ext3_ordered_write_end, - .bmap = ext3_bmap, - .invalidatepage = ext3_invalidatepage, - .releasepage = ext3_releasepage, - .direct_IO = ext3_direct_IO, - .migratepage = buffer_migrate_page, + .readpage = ext3_readpage, + .readpages = ext3_readpages, + .writepage = ext3_ordered_writepage, + .sync_page = block_sync_page, + .write_begin = ext3_write_begin, + .write_end = ext3_ordered_write_end, + .bmap = ext3_bmap, + .invalidatepage = ext3_invalidatepage, + .releasepage = ext3_releasepage, + .direct_IO = ext3_direct_IO, + .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; static const struct address_space_operations ext3_writeback_aops = { - .readpage = ext3_readpage, - .readpages = ext3_readpages, - .writepage = ext3_writeback_writepage, - .sync_page = block_sync_page, - .write_begin = ext3_write_begin, - .write_end = ext3_writeback_write_end, - .bmap = ext3_bmap, - .invalidatepage = ext3_invalidatepage, - .releasepage = ext3_releasepage, - .direct_IO = ext3_direct_IO, - .migratepage = buffer_migrate_page, + .readpage = ext3_readpage, + .readpages = ext3_readpages, + .writepage = ext3_writeback_writepage, + .sync_page = block_sync_page, + .write_begin = ext3_write_begin, + .write_end = ext3_writeback_write_end, + .bmap = ext3_bmap, + .invalidatepage = ext3_invalidatepage, + .releasepage = ext3_releasepage, + .direct_IO = ext3_direct_IO, + .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; static const struct address_space_operations ext3_journalled_aops = { - .readpage = ext3_readpage, - .readpages = ext3_readpages, - .writepage = ext3_journalled_writepage, - .sync_page = block_sync_page, - .write_begin = ext3_write_begin, - .write_end = ext3_journalled_write_end, - .set_page_dirty = ext3_journalled_set_page_dirty, - .bmap = ext3_bmap, - .invalidatepage = ext3_invalidatepage, - .releasepage = ext3_releasepage, + .readpage = ext3_readpage, + .readpages = ext3_readpages, + .writepage = ext3_journalled_writepage, + .sync_page = block_sync_page, + .write_begin = ext3_write_begin, + .write_end = ext3_journalled_write_end, + .set_page_dirty = ext3_journalled_set_page_dirty, + .bmap = ext3_bmap, + .invalidatepage = ext3_invalidatepage, + .releasepage = ext3_releasepage, + .is_partially_uptodate = block_is_partially_uptodate, }; void ext3_set_aops(struct inode *inode) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 8ca2763df09..9843b046c23 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2806,59 +2806,63 @@ static int ext4_journalled_set_page_dirty(struct page *page) } static const struct address_space_operations ext4_ordered_aops = { - .readpage = ext4_readpage, - .readpages = ext4_readpages, - .writepage = ext4_normal_writepage, - .sync_page = block_sync_page, - .write_begin = ext4_write_begin, - .write_end = ext4_ordered_write_end, - .bmap = ext4_bmap, - .invalidatepage = ext4_invalidatepage, - .releasepage = ext4_releasepage, - .direct_IO = ext4_direct_IO, - .migratepage = buffer_migrate_page, + .readpage = ext4_readpage, + .readpages = ext4_readpages, + .writepage = ext4_normal_writepage, + .sync_page = block_sync_page, + .write_begin = ext4_write_begin, + .write_end = ext4_ordered_write_end, + .bmap = ext4_bmap, + .invalidatepage = ext4_invalidatepage, + .releasepage = ext4_releasepage, + .direct_IO = ext4_direct_IO, + .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; static const struct address_space_operations ext4_writeback_aops = { - .readpage = ext4_readpage, - .readpages = ext4_readpages, - .writepage = ext4_normal_writepage, - .sync_page = block_sync_page, - .write_begin = ext4_write_begin, - .write_end = ext4_writeback_write_end, - .bmap = ext4_bmap, - .invalidatepage = ext4_invalidatepage, - .releasepage = ext4_releasepage, - .direct_IO = ext4_direct_IO, - .migratepage = buffer_migrate_page, + .readpage = ext4_readpage, + .readpages = ext4_readpages, + .writepage = ext4_normal_writepage, + .sync_page = block_sync_page, + .write_begin = ext4_write_begin, + .write_end = ext4_writeback_write_end, + .bmap = ext4_bmap, + .invalidatepage = ext4_invalidatepage, + .releasepage = ext4_releasepage, + .direct_IO = ext4_direct_IO, + .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; static const struct address_space_operations ext4_journalled_aops = { - .readpage = ext4_readpage, - .readpages = ext4_readpages, - .writepage = ext4_journalled_writepage, - .sync_page = block_sync_page, - .write_begin = ext4_write_begin, - .write_end = ext4_journalled_write_end, - .set_page_dirty = ext4_journalled_set_page_dirty, - .bmap = ext4_bmap, - .invalidatepage = ext4_invalidatepage, - .releasepage = ext4_releasepage, + .readpage = ext4_readpage, + .readpages = ext4_readpages, + .writepage = ext4_journalled_writepage, + .sync_page = block_sync_page, + .write_begin = ext4_write_begin, + .write_end = ext4_journalled_write_end, + .set_page_dirty = ext4_journalled_set_page_dirty, + .bmap = ext4_bmap, + .invalidatepage = ext4_invalidatepage, + .releasepage = ext4_releasepage, + .is_partially_uptodate = block_is_partially_uptodate, }; static const struct address_space_operations ext4_da_aops = { - .readpage = ext4_readpage, - .readpages = ext4_readpages, - .writepage = ext4_da_writepage, - .writepages = ext4_da_writepages, - .sync_page = block_sync_page, - .write_begin = ext4_da_write_begin, - .write_end = ext4_da_write_end, - .bmap = ext4_bmap, - .invalidatepage = ext4_da_invalidatepage, - .releasepage = ext4_releasepage, - .direct_IO = ext4_direct_IO, - .migratepage = buffer_migrate_page, + .readpage = ext4_readpage, + .readpages = ext4_readpages, + .writepage = ext4_da_writepage, + .writepages = ext4_da_writepages, + .sync_page = block_sync_page, + .write_begin = ext4_da_write_begin, + .write_end = ext4_da_write_end, + .bmap = ext4_bmap, + .invalidatepage = ext4_da_invalidatepage, + .releasepage = ext4_releasepage, + .direct_IO = ext4_direct_IO, + .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; void ext4_set_aops(struct inode *inode) diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 82aa36c53ea..50cfe8ceb47 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -205,6 +205,8 @@ void block_invalidatepage(struct page *page, unsigned long offset); int block_write_full_page(struct page *page, get_block_t *get_block, struct writeback_control *wbc); int block_read_full_page(struct page*, get_block_t*); +int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, + unsigned long from); int block_write_begin(struct file *, struct address_space *, loff_t, unsigned, unsigned, struct page **, void **, get_block_t*); diff --git a/include/linux/fs.h b/include/linux/fs.h index 8252b045e62..580b513668f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -443,6 +443,27 @@ static inline size_t iov_iter_count(struct iov_iter *i) return i->count; } +/* + * "descriptor" for what we're up to with a read. + * This allows us to use the same read code yet + * have multiple different users of the data that + * we read from a file. + * + * The simplest case just copies the data to user + * mode. + */ +typedef struct { + size_t written; + size_t count; + union { + char __user *buf; + void *data; + } arg; + int error; +} read_descriptor_t; + +typedef int (*read_actor_t)(read_descriptor_t *, struct page *, + unsigned long, unsigned long); struct address_space_operations { int (*writepage)(struct page *page, struct writeback_control *wbc); @@ -484,6 +505,8 @@ struct address_space_operations { int (*migratepage) (struct address_space *, struct page *, struct page *); int (*launder_page) (struct page *); + int (*is_partially_uptodate) (struct page *, read_descriptor_t *, + unsigned long); }; /* @@ -1198,27 +1221,6 @@ struct block_device_operations { struct module *owner; }; -/* - * "descriptor" for what we're up to with a read. - * This allows us to use the same read code yet - * have multiple different users of the data that - * we read from a file. - * - * The simplest case just copies the data to user - * mode. - */ -typedef struct { - size_t written; - size_t count; - union { - char __user * buf; - void *data; - } arg; - int error; -} read_descriptor_t; - -typedef int (*read_actor_t)(read_descriptor_t *, struct page *, unsigned long, unsigned long); - /* These macros are for out of kernel modules to test that * the kernel supports the unlocked_ioctl and compat_ioctl * fields in struct file_operations. */ diff --git a/mm/filemap.c b/mm/filemap.c index 5de7633e1db..42bbc6909ba 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1023,8 +1023,17 @@ find_page: ra, filp, page, index, last_index - index); } - if (!PageUptodate(page)) - goto page_not_up_to_date; + if (!PageUptodate(page)) { + if (inode->i_blkbits == PAGE_CACHE_SHIFT || + !mapping->a_ops->is_partially_uptodate) + goto page_not_up_to_date; + if (TestSetPageLocked(page)) + goto page_not_up_to_date; + if (!mapping->a_ops->is_partially_uptodate(page, + desc, offset)) + goto page_not_up_to_date_locked; + unlock_page(page); + } page_ok: /* * i_size must be checked after we know the page is Uptodate. @@ -1094,6 +1103,7 @@ page_not_up_to_date: if (lock_page_killable(page)) goto readpage_eio; +page_not_up_to_date_locked: /* Did it get truncated before we got the lock? */ if (!page->mapping) { unlock_page(page); -- cgit v1.2.3-70-g09d2 From 94ad374a0751f40d25e22e036c37f7263569d24c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 30 Jul 2008 14:45:12 -0700 Subject: Fix off-by-one error in iov_iter_advance() The iov_iter_advance() function would look at the iov->iov_len entry even though it might have iterated over the whole array, and iov was pointing past the end. This would cause DEBUG_PAGEALLOC to trigger a kernel page fault if the allocation was at the end of a page, and the next page was unallocated. The quick fix is to just change the order of the tests: check that there is any iovec data left before we check the iov entry itself. Thanks to Alexey Dobriyan for finding this case, and testing the fix. Reported-and-tested-by: Alexey Dobriyan Cc: Nick Piggin Cc: Andrew Morton Cc: [2.6.25.x, 2.6.26.x] Signed-off-by: Linus Torvalds --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 42bbc6909ba..d97d1ad5547 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1879,7 +1879,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes) * The !iov->iov_len check ensures we skip over unlikely * zero-length segments (without overruning the iovec). */ - while (bytes || unlikely(!iov->iov_len && i->count)) { + while (bytes || unlikely(i->count && !iov->iov_len)) { int copy; copy = min(bytes, iov->iov_len - base); -- cgit v1.2.3-70-g09d2 From 529ae9aaa08378cfe2a4350bded76f32cc8ff0ce Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Sat, 2 Aug 2008 12:01:03 +0200 Subject: mm: rename page trylock Converting page lock to new locking bitops requires a change of page flag operation naming, so we might as well convert it to something nicer (!TestSetPageLocked_Lock => trylock_page, SetPageLocked => set_page_locked). This also facilitates lockdeping of page lock. Signed-off-by: Nick Piggin Acked-by: KOSAKI Motohiro Acked-by: Peter Zijlstra Acked-by: Andrew Morton Acked-by: Benjamin Herrenschmidt Signed-off-by: Linus Torvalds --- drivers/scsi/sg.c | 2 +- fs/afs/write.c | 2 +- fs/cifs/file.c | 2 +- fs/jbd/commit.c | 4 +-- fs/jbd2/commit.c | 2 +- fs/reiserfs/journal.c | 2 +- fs/splice.c | 2 +- fs/xfs/linux-2.6/xfs_aops.c | 4 +-- include/linux/page-flags.h | 2 +- include/linux/pagemap.h | 67 +++++++++++++++++++++++++++------------------ mm/filemap.c | 12 ++++---- mm/memory.c | 2 +- mm/migrate.c | 4 +-- mm/rmap.c | 2 +- mm/shmem.c | 4 +-- mm/swap.c | 2 +- mm/swap_state.c | 8 +++--- mm/swapfile.c | 2 +- mm/truncate.c | 4 +-- mm/vmscan.c | 4 +-- 20 files changed, 74 insertions(+), 59 deletions(-) (limited to 'mm/filemap.c') diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index d3b8ebb8377..3d36270a8b4 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -1747,7 +1747,7 @@ st_map_user_pages(struct scatterlist *sgl, const unsigned int max_pages, */ flush_dcache_page(pages[i]); /* ?? Is locking needed? I don't think so */ - /* if (TestSetPageLocked(pages[i])) + /* if (!trylock_page(pages[i])) goto out_unlock; */ } diff --git a/fs/afs/write.c b/fs/afs/write.c index 9a849ad3c48..065b4e10681 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -404,7 +404,7 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb, page = pages[loop]; if (page->index > wb->last) break; - if (TestSetPageLocked(page)) + if (!trylock_page(page)) break; if (!PageDirty(page) || page_private(page) != (unsigned long) wb) { diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 0aac824371a..e692c42f24b 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -1280,7 +1280,7 @@ retry: if (first < 0) lock_page(page); - else if (TestSetPageLocked(page)) + else if (!trylock_page(page)) break; if (unlikely(page->mapping != mapping)) { diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c index 2eccbfaa1d4..81a9ad7177c 100644 --- a/fs/jbd/commit.c +++ b/fs/jbd/commit.c @@ -63,7 +63,7 @@ static void release_buffer_page(struct buffer_head *bh) goto nope; /* OK, it's a truncated page */ - if (TestSetPageLocked(page)) + if (!trylock_page(page)) goto nope; page_cache_get(page); @@ -446,7 +446,7 @@ void journal_commit_transaction(journal_t *journal) spin_lock(&journal->j_list_lock); } if (unlikely(!buffer_uptodate(bh))) { - if (TestSetPageLocked(bh->b_page)) { + if (!trylock_page(bh->b_page)) { spin_unlock(&journal->j_list_lock); lock_page(bh->b_page); spin_lock(&journal->j_list_lock); diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index adf0395f318..f2ad061e95e 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -67,7 +67,7 @@ static void release_buffer_page(struct buffer_head *bh) goto nope; /* OK, it's a truncated page */ - if (TestSetPageLocked(page)) + if (!trylock_page(page)) goto nope; page_cache_get(page); diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c index c8f60ee183b..ce2208b2711 100644 --- a/fs/reiserfs/journal.c +++ b/fs/reiserfs/journal.c @@ -627,7 +627,7 @@ static int journal_list_still_alive(struct super_block *s, static void release_buffer_page(struct buffer_head *bh) { struct page *page = bh->b_page; - if (!page->mapping && !TestSetPageLocked(page)) { + if (!page->mapping && trylock_page(page)) { page_cache_get(page); put_bh(bh); if (!page->mapping) diff --git a/fs/splice.c b/fs/splice.c index b30311ba8af..1bbc6f4bb09 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -371,7 +371,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, * for an in-flight io page */ if (flags & SPLICE_F_NONBLOCK) { - if (TestSetPageLocked(page)) { + if (!trylock_page(page)) { error = -EAGAIN; break; } diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index 0b211cba190..fa73179233a 100644 --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -675,7 +675,7 @@ xfs_probe_cluster( } else pg_offset = PAGE_CACHE_SIZE; - if (page->index == tindex && !TestSetPageLocked(page)) { + if (page->index == tindex && trylock_page(page)) { pg_len = xfs_probe_page(page, pg_offset, mapped); unlock_page(page); } @@ -759,7 +759,7 @@ xfs_convert_page( if (page->index != tindex) goto fail; - if (TestSetPageLocked(page)) + if (!trylock_page(page)) goto fail; if (PageWriteback(page)) goto fail_unlock_page; diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 25aaccdb2f2..c74d3e87531 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -163,7 +163,7 @@ static inline int Page##uname(struct page *page) \ struct page; /* forward declaration */ -PAGEFLAG(Locked, locked) TESTSCFLAG(Locked, locked) +TESTPAGEFLAG(Locked, locked) PAGEFLAG(Error, error) PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced) PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 69ed3cb1197..5da31c12101 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -250,29 +250,6 @@ static inline struct page *read_mapping_page(struct address_space *mapping, return read_cache_page(mapping, index, filler, data); } -int add_to_page_cache_locked(struct page *page, struct address_space *mapping, - pgoff_t index, gfp_t gfp_mask); -int add_to_page_cache_lru(struct page *page, struct address_space *mapping, - pgoff_t index, gfp_t gfp_mask); -extern void remove_from_page_cache(struct page *page); -extern void __remove_from_page_cache(struct page *page); - -/* - * Like add_to_page_cache_locked, but used to add newly allocated pages: - * the page is new, so we can just run SetPageLocked() against it. - */ -static inline int add_to_page_cache(struct page *page, - struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) -{ - int error; - - SetPageLocked(page); - error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); - if (unlikely(error)) - ClearPageLocked(page); - return error; -} - /* * Return byte-offset into filesystem object for page. */ @@ -294,13 +271,28 @@ extern int __lock_page_killable(struct page *page); extern void __lock_page_nosync(struct page *page); extern void unlock_page(struct page *page); +static inline void set_page_locked(struct page *page) +{ + set_bit(PG_locked, &page->flags); +} + +static inline void clear_page_locked(struct page *page) +{ + clear_bit(PG_locked, &page->flags); +} + +static inline int trylock_page(struct page *page) +{ + return !test_and_set_bit(PG_locked, &page->flags); +} + /* * lock_page may only be called if we have the page's inode pinned. */ static inline void lock_page(struct page *page) { might_sleep(); - if (TestSetPageLocked(page)) + if (!trylock_page(page)) __lock_page(page); } @@ -312,7 +304,7 @@ static inline void lock_page(struct page *page) static inline int lock_page_killable(struct page *page) { might_sleep(); - if (TestSetPageLocked(page)) + if (!trylock_page(page)) return __lock_page_killable(page); return 0; } @@ -324,7 +316,7 @@ static inline int lock_page_killable(struct page *page) static inline void lock_page_nosync(struct page *page) { might_sleep(); - if (TestSetPageLocked(page)) + if (!trylock_page(page)) __lock_page_nosync(page); } @@ -409,4 +401,27 @@ static inline int fault_in_pages_readable(const char __user *uaddr, int size) return ret; } +int add_to_page_cache_locked(struct page *page, struct address_space *mapping, + pgoff_t index, gfp_t gfp_mask); +int add_to_page_cache_lru(struct page *page, struct address_space *mapping, + pgoff_t index, gfp_t gfp_mask); +extern void remove_from_page_cache(struct page *page); +extern void __remove_from_page_cache(struct page *page); + +/* + * Like add_to_page_cache_locked, but used to add newly allocated pages: + * the page is new, so we can just run set_page_locked() against it. + */ +static inline int add_to_page_cache(struct page *page, + struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) +{ + int error; + + set_page_locked(page); + error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); + if (unlikely(error)) + clear_page_locked(page); + return error; +} + #endif /* _LINUX_PAGEMAP_H */ diff --git a/mm/filemap.c b/mm/filemap.c index d97d1ad5547..54e96865085 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -558,14 +558,14 @@ EXPORT_SYMBOL(wait_on_page_bit); * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. * * The first mb is necessary to safely close the critical section opened by the - * TestSetPageLocked(), the second mb is necessary to enforce ordering between - * the clear_bit and the read of the waitqueue (to avoid SMP races with a - * parallel wait_on_page_locked()). + * test_and_set_bit() to lock the page; the second mb is necessary to enforce + * ordering between the clear_bit and the read of the waitqueue (to avoid SMP + * races with a parallel wait_on_page_locked()). */ void unlock_page(struct page *page) { smp_mb__before_clear_bit(); - if (!TestClearPageLocked(page)) + if (!test_and_clear_bit(PG_locked, &page->flags)) BUG(); smp_mb__after_clear_bit(); wake_up_page(page, PG_locked); @@ -931,7 +931,7 @@ grab_cache_page_nowait(struct address_space *mapping, pgoff_t index) struct page *page = find_get_page(mapping, index); if (page) { - if (!TestSetPageLocked(page)) + if (trylock_page(page)) return page; page_cache_release(page); return NULL; @@ -1027,7 +1027,7 @@ find_page: if (inode->i_blkbits == PAGE_CACHE_SHIFT || !mapping->a_ops->is_partially_uptodate) goto page_not_up_to_date; - if (TestSetPageLocked(page)) + if (!trylock_page(page)) goto page_not_up_to_date; if (!mapping->a_ops->is_partially_uptodate(page, desc, offset)) diff --git a/mm/memory.c b/mm/memory.c index a472bcd4b06..1002f473f49 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1789,7 +1789,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, * not dirty accountable. */ if (PageAnon(old_page)) { - if (!TestSetPageLocked(old_page)) { + if (trylock_page(old_page)) { reuse = can_share_swap_page(old_page); unlock_page(old_page); } diff --git a/mm/migrate.c b/mm/migrate.c index 153572fb60b..2a80136b23b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -605,7 +605,7 @@ static int move_to_new_page(struct page *newpage, struct page *page) * establishing additional references. We are the only one * holding a reference to the new page at this point. */ - if (TestSetPageLocked(newpage)) + if (!trylock_page(newpage)) BUG(); /* Prepare mapping for the new page.*/ @@ -667,7 +667,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, BUG_ON(charge); rc = -EAGAIN; - if (TestSetPageLocked(page)) { + if (!trylock_page(page)) { if (!force) goto move_newpage; lock_page(page); diff --git a/mm/rmap.c b/mm/rmap.c index 94a5246a3f9..1ea4e6fcee7 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -422,7 +422,7 @@ int page_referenced(struct page *page, int is_locked, referenced += page_referenced_anon(page, mem_cont); else if (is_locked) referenced += page_referenced_file(page, mem_cont); - else if (TestSetPageLocked(page)) + else if (!trylock_page(page)) referenced++; else { if (page->mapping) diff --git a/mm/shmem.c b/mm/shmem.c index c1e5a3b4f75..04fb4f1ab88 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1265,7 +1265,7 @@ repeat: } /* We have to do this with page locked to prevent races */ - if (TestSetPageLocked(swappage)) { + if (!trylock_page(swappage)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); wait_on_page_locked(swappage); @@ -1329,7 +1329,7 @@ repeat: shmem_swp_unmap(entry); filepage = find_get_page(mapping, idx); if (filepage && - (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { + (!PageUptodate(filepage) || !trylock_page(filepage))) { spin_unlock(&info->lock); wait_on_page_locked(filepage); page_cache_release(filepage); diff --git a/mm/swap.c b/mm/swap.c index 7417a2adbe5..9e0cb311807 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -444,7 +444,7 @@ void pagevec_strip(struct pagevec *pvec) for (i = 0; i < pagevec_count(pvec); i++) { struct page *page = pvec->pages[i]; - if (PagePrivate(page) && !TestSetPageLocked(page)) { + if (PagePrivate(page) && trylock_page(page)) { if (PagePrivate(page)) try_to_release_page(page, 0); unlock_page(page); diff --git a/mm/swap_state.c b/mm/swap_state.c index b8035b05512..167cf2dc8a0 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -201,7 +201,7 @@ void delete_from_swap_cache(struct page *page) */ static inline void free_swap_cache(struct page *page) { - if (PageSwapCache(page) && !TestSetPageLocked(page)) { + if (PageSwapCache(page) && trylock_page(page)) { remove_exclusive_swap_page(page); unlock_page(page); } @@ -302,9 +302,9 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, * re-using the just freed swap entry for an existing page. * May fail (-ENOMEM) if radix-tree node allocation failed. */ - SetPageLocked(new_page); + set_page_locked(new_page); err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL); - if (!err) { + if (likely(!err)) { /* * Initiate read into locked page and return. */ @@ -312,7 +312,7 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, swap_readpage(NULL, new_page); return new_page; } - ClearPageLocked(new_page); + clear_page_locked(new_page); swap_free(entry); } while (err != -ENOMEM); diff --git a/mm/swapfile.c b/mm/swapfile.c index bb7f79641f9..1e330f2998f 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -403,7 +403,7 @@ void free_swap_and_cache(swp_entry_t entry) if (p) { if (swap_entry_free(p, swp_offset(entry)) == 1) { page = find_get_page(&swapper_space, entry.val); - if (page && unlikely(TestSetPageLocked(page))) { + if (page && unlikely(!trylock_page(page))) { page_cache_release(page); page = NULL; } diff --git a/mm/truncate.c b/mm/truncate.c index 894e9a70699..250505091d3 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -187,7 +187,7 @@ void truncate_inode_pages_range(struct address_space *mapping, if (page_index > next) next = page_index; next++; - if (TestSetPageLocked(page)) + if (!trylock_page(page)) continue; if (PageWriteback(page)) { unlock_page(page); @@ -280,7 +280,7 @@ unsigned long __invalidate_mapping_pages(struct address_space *mapping, pgoff_t index; int lock_failed; - lock_failed = TestSetPageLocked(page); + lock_failed = !trylock_page(page); /* * We really shouldn't be looking at the ->index of an diff --git a/mm/vmscan.c b/mm/vmscan.c index 75be453628b..1ff1a58e7c1 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -496,7 +496,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, page = lru_to_page(page_list); list_del(&page->lru); - if (TestSetPageLocked(page)) + if (!trylock_page(page)) goto keep; VM_BUG_ON(PageActive(page)); @@ -582,7 +582,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, * A synchronous write - probably a ramdisk. Go * ahead and try to reclaim the page. */ - if (TestSetPageLocked(page)) + if (!trylock_page(page)) goto keep; if (PageDirty(page) || PageWriteback(page)) goto keep_locked; -- cgit v1.2.3-70-g09d2