diff options
| -rw-r--r-- | fs/fuse/dev.c | 19 | ||||
| -rw-r--r-- | fs/fuse/dir.c | 84 | ||||
| -rw-r--r-- | fs/fuse/file.c | 321 | ||||
| -rw-r--r-- | fs/fuse/fuse_i.h | 37 | ||||
| -rw-r--r-- | fs/fuse/inode.c | 49 |
5 files changed, 481 insertions, 29 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index af639807524..bba83762c48 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -47,6 +47,14 @@ struct fuse_req *fuse_request_alloc(void) return req; } +struct fuse_req *fuse_request_alloc_nofs(void) +{ + struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_NOFS); + if (req) + fuse_request_init(req); + return req; +} + void fuse_request_free(struct fuse_req *req) { kmem_cache_free(fuse_req_cachep, req); @@ -430,6 +438,17 @@ void request_send_background(struct fuse_conn *fc, struct fuse_req *req) } /* + * Called under fc->lock + * + * fc->connected must have been checked previously + */ +void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req) +{ + req->isreply = 1; + request_send_nowait_locked(fc, req); +} + +/* * Lock the request. Up to the next unlock_request() there mustn't be * anything that could cause a page-fault. If the request was already * aborted bail out. diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index c4807b3fc8a..48b9971ecd9 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1107,6 +1107,50 @@ static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg) } /* + * Prevent concurrent writepages on inode + * + * This is done by adding a negative bias to the inode write counter + * and waiting for all pending writes to finish. + */ +void fuse_set_nowrite(struct inode *inode) +{ + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + + BUG_ON(!mutex_is_locked(&inode->i_mutex)); + + spin_lock(&fc->lock); + BUG_ON(fi->writectr < 0); + fi->writectr += FUSE_NOWRITE; + spin_unlock(&fc->lock); + wait_event(fi->page_waitq, fi->writectr == FUSE_NOWRITE); +} + +/* + * Allow writepages on inode + * + * Remove the bias from the writecounter and send any queued + * writepages. + */ +static void __fuse_release_nowrite(struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + + BUG_ON(fi->writectr != FUSE_NOWRITE); + fi->writectr = 0; + fuse_flush_writepages(inode); +} + +void fuse_release_nowrite(struct inode *inode) +{ + struct fuse_conn *fc = get_fuse_conn(inode); + + spin_lock(&fc->lock); + __fuse_release_nowrite(inode); + spin_unlock(&fc->lock); +} + +/* * Set attributes, and at the same time refresh them. * * Truncation is slightly complicated, because the 'truncate' request @@ -1122,6 +1166,8 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr, struct fuse_req *req; struct fuse_setattr_in inarg; struct fuse_attr_out outarg; + bool is_truncate = false; + loff_t oldsize; int err; if (!fuse_allow_task(fc, current)) @@ -1145,12 +1191,16 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr, send_sig(SIGXFSZ, current, 0); return -EFBIG; } + is_truncate = true; } req = fuse_get_req(fc); if (IS_ERR(req)) return PTR_ERR(req); + if (is_truncate) + fuse_set_nowrite(inode); + memset(&inarg, 0, sizeof(inarg)); memset(&outarg, 0, sizeof(outarg)); iattr_to_fattr(attr, &inarg); @@ -1181,16 +1231,44 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr, if (err) { if (err == -EINTR) fuse_invalidate_attr(inode); - return err; + goto error; } if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) { make_bad_inode(inode); - return -EIO; + err = -EIO; + goto error; + } + + spin_lock(&fc->lock); + fuse_change_attributes_common(inode, &outarg.attr, + attr_timeout(&outarg)); + oldsize = inode->i_size; + i_size_write(inode, outarg.attr.size); + + if (is_truncate) { + /* NOTE: this may release/reacquire fc->lock */ + __fuse_release_nowrite(inode); + } + spin_unlock(&fc->lock); + + /* + * Only call invalidate_inode_pages2() after removing + * FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock. + */ + if (S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) { + if (outarg.attr.size < oldsize) + fuse_truncate(inode->i_mapping, outarg.attr.size); + invalidate_inode_pages2(inode->i_mapping); } - fuse_change_attributes(inode, &outarg.attr, attr_timeout(&outarg), 0); return 0; + +error: + if (is_truncate) + fuse_release_nowrite(inode); + + return err; } static int fuse_setattr(struct dentry *entry, struct iattr *attr) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 676b0bc8a86..68051f3bdf9 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -210,6 +210,49 @@ u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id) return (u64) v0 + ((u64) v1 << 32); } +/* + * Check if page is under writeback + * + * This is currently done by walking the list of writepage requests + * for the inode, which can be pretty inefficient. + */ +static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index) +{ + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + struct fuse_req *req; + bool found = false; + + spin_lock(&fc->lock); + list_for_each_entry(req, &fi->writepages, writepages_entry) { + pgoff_t curr_index; + + BUG_ON(req->inode != inode); + curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT; + if (curr_index == index) { + found = true; + break; + } + } + spin_unlock(&fc->lock); + + return found; +} + +/* + * Wait for page writeback to be completed. + * + * Since fuse doesn't rely on the VM writeback tracking, this has to + * use some other means. + */ +static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + + wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index)); + return 0; +} + static int fuse_flush(struct file *file, fl_owner_t id) { struct inode *inode = file->f_path.dentry->d_inode; @@ -245,6 +288,21 @@ static int fuse_flush(struct file *file, fl_owner_t id) return err; } +/* + * Wait for all pending writepages on the inode to finish. + * + * This is currently done by blocking further writes with FUSE_NOWRITE + * and waiting for all sent writes to complete. + * + * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage + * could conflict with truncation. + */ +static void fuse_sync_writes(struct inode *inode) +{ + fuse_set_nowrite(inode); + fuse_release_nowrite(inode); +} + int fuse_fsync_common(struct file *file, struct dentry *de, int datasync, int isdir) { @@ -261,6 +319,17 @@ int fuse_fsync_common(struct file *file, struct dentry *de, int datasync, if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir)) return 0; + /* + * Start writeback against all dirty pages of the inode, then + * wait for all outstanding writes, before sending the FSYNC + * request. + */ + err = write_inode_now(inode, 0); + if (err) + return err; + + fuse_sync_writes(inode); + req = fuse_get_req(fc); if (IS_ERR(req)) return PTR_ERR(req); @@ -340,6 +409,13 @@ static int fuse_readpage(struct file *file, struct page *page) if (is_bad_inode(inode)) goto out; + /* + * Page writeback can extend beyond the liftime of the + * page-cache page, so make sure we read a properly synced + * page. + */ + fuse_wait_on_page_writeback(inode, page->index); + req = fuse_get_req(fc); err = PTR_ERR(req); if (IS_ERR(req)) @@ -411,6 +487,8 @@ static int fuse_readpages_fill(void *_data, struct page *page) struct inode *inode = data->inode; struct fuse_conn *fc = get_fuse_conn(inode); + fuse_wait_on_page_writeback(inode, page->index); + if (req->num_pages && (req->num_pages == FUSE_MAX_PAGES_PER_REQ || (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read || @@ -477,11 +555,10 @@ static ssize_t fuse_file_aio_read(struct kiocb *iocb, const struct iovec *iov, } static void fuse_write_fill(struct fuse_req *req, struct file *file, - struct inode *inode, loff_t pos, size_t count, - int writepage) + struct fuse_file *ff, struct inode *inode, + loff_t pos, size_t count, int writepage) { struct fuse_conn *fc = get_fuse_conn(inode); - struct fuse_file *ff = file->private_data; struct fuse_write_in *inarg = &req->misc.write.in; struct fuse_write_out *outarg = &req->misc.write.out; @@ -490,7 +567,7 @@ static void fuse_write_fill(struct fuse_req *req, struct file *file, inarg->offset = pos; inarg->size = count; inarg->write_flags = writepage ? FUSE_WRITE_CACHE : 0; - inarg->flags = file->f_flags; + inarg->flags = file ? file->f_flags : 0; req->in.h.opcode = FUSE_WRITE; req->in.h.nodeid = get_node_id(inode); req->in.argpages = 1; @@ -511,7 +588,7 @@ static size_t fuse_send_write(struct fuse_req *req, struct file *file, fl_owner_t owner) { struct fuse_conn *fc = get_fuse_conn(inode); - fuse_write_fill(req, file, inode, pos, count, 0); + fuse_write_fill(req, file, file->private_data, inode, pos, count, 0); if (owner != NULL) { struct fuse_write_in *inarg = &req->misc.write.in; inarg->write_flags |= FUSE_WRITE_LOCKOWNER; @@ -546,6 +623,12 @@ static int fuse_buffered_write(struct file *file, struct inode *inode, if (is_bad_inode(inode)) return -EIO; + /* + * Make sure writepages on the same page are not mixed up with + * plain writes. + */ + fuse_wait_on_page_writeback(inode, page->index); + req = fuse_get_req(fc); if (IS_ERR(req)) return PTR_ERR(req); @@ -716,21 +799,225 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf, return res; } -static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) +static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req) { - if ((vma->vm_flags & VM_SHARED)) { - if ((vma->vm_flags & VM_WRITE)) - return -ENODEV; - else - vma->vm_flags &= ~VM_MAYWRITE; + __free_page(req->pages[0]); + fuse_file_put(req->ff); + fuse_put_request(fc, req); +} + +static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req) +{ + struct inode *inode = req->inode; + struct fuse_inode *fi = get_fuse_inode(inode); + struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info; + + list_del(&req->writepages_entry); + dec_bdi_stat(bdi, BDI_WRITEBACK); + dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP); + bdi_writeout_inc(bdi); + wake_up(&fi->page_waitq); +} + +/* Called under fc->lock, may release and reacquire it */ +static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req) +{ + struct fuse_inode *fi = get_fuse_inode(req->inode); + loff_t size = i_size_read(req->inode); + struct fuse_write_in *inarg = &req->misc.write.in; + + if (!fc->connected) + goto out_free; + + if (inarg->offset + PAGE_CACHE_SIZE <= size) { + inarg->size = PAGE_CACHE_SIZE; + } else if (inarg->offset < size) { + inarg->size = size & (PAGE_CACHE_SIZE - 1); + } else { + /* Got truncated off completely */ + goto out_free; } - return generic_file_mmap(file, vma); + + req->in.args[1].size = inarg->size; + fi->writectr++; + request_send_background_locked(fc, req); + return; + + out_free: + fuse_writepage_finish(fc, req); + spin_unlock(&fc->lock); + fuse_writepage_free(fc, req); + spin_lock(&fc->lock); } -static int fuse_set_page_dirty(struct page *page) +/* + * If fi->writectr is positive (no truncate or fsync going on) send + * all queued writepage requests. + * + * Called with fc->lock + */ +void fuse_flush_writepages(struct inode *inode) { - printk("fuse_set_page_dirty: should not happen\n"); - dump_stack(); + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + struct fuse_req *req; + + while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) { + req = list_entry(fi->queued_writes.next, struct fuse_req, list); + list_del_init(&req->list); + fuse_send_writepage(fc, req); + } +} + +static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req) +{ + struct inode *inode = req->inode; + struct fuse_inode *fi = get_fuse_inode(inode); + + mapping_set_error(inode->i_mapping, req->out.h.error); + spin_lock(&fc->lock); + fi->writectr--; + fuse_writepage_finish(fc, req); + spin_unlock(&fc->lock); + fuse_writepage_free(fc, req); +} + +static int fuse_writepage_locked(struct page *page) +{ + struct address_space *mapping = page->mapping; + struct inode *inode = mapping->host; + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + struct fuse_req *req; + struct fuse_file *ff; + struct page *tmp_page; + + set_page_writeback(page); + + req = fuse_request_alloc_nofs(); + if (!req) + goto err; + + tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!tmp_page) + goto err_free; + + spin_lock(&fc->lock); + BUG_ON(list_empty(&fi->write_files)); + ff = list_entry(fi->write_files.next, struct fuse_file, write_entry); + req->ff = fuse_file_get(ff); + spin_unlock(&fc->lock); + + fuse_write_fill(req, NULL, ff, inode, page_offset(page), 0, 1); + + copy_highpage(tmp_page, page); + req->num_pages = 1; + req->pages[0] = tmp_page; + req->page_offset = 0; + req->end = fuse_writepage_end; + req->inode = inode; + + inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK); + inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP); + end_page_writeback(page); + + spin_lock(&fc->lock); + list_add(&req->writepages_entry, &fi->writepages); + list_add_tail(&req->list, &fi->queued_writes); + fuse_flush_writepages(inode); + spin_unlock(&fc->lock); + + return 0; + +err_free: + fuse_request_free(req); +err: + end_page_writeback(page); + return -ENOMEM; +} + +static int fuse_writepage(struct page *page, struct writeback_control *wbc) +{ + int err; + + err = fuse_writepage_locked(page); + unlock_page(page); + + return err; +} + +static int fuse_launder_page(struct page *page) +{ + int err = 0; + if (clear_page_dirty_for_io(page)) { + struct inode *inode = page->mapping->host; + err = fuse_writepage_locked(page); + if (!err) + fuse_wait_on_page_writeback(inode, page->index); + } + return err; +} + +/* + * Write back dirty pages now, because there may not be any suitable + * open files later + */ +static void fuse_vma_close(struct vm_area_struct *vma) +{ + filemap_write_and_wait(vma->vm_file->f_mapping); +} + +/* + * Wait for writeback against this page to complete before allowing it + * to be marked dirty again, and hence written back again, possibly + * before the previous writepage completed. + * + * Block here, instead of in ->writepage(), so that the userspace fs + * can only block processes actually operating on the filesystem. + * + * Otherwise unprivileged userspace fs would be able to block + * unrelated: + * + * - page migration + * - sync(2) + * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER + */ +static int fuse_page_mkwrite(struct vm_area_struct *vma, struct page *page) +{ + /* + * Don't use page->mapping as it may become NULL from a + * concurrent truncate. + */ + struct inode *inode = vma->vm_file->f_mapping->host; + + fuse_wait_on_page_writeback(inode, page->index); + return 0; +} + +static struct vm_operations_struct fuse_file_vm_ops = { + .close = fuse_vma_close, + .fault = filemap_fault, + .page_mkwrite = fuse_page_mkwrite, +}; + +static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) +{ + if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) { + struct inode *inode = file->f_dentry->d_inode; + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + struct fuse_file *ff = file->private_data; + /* + * file may be written through mmap, so chain it onto the + * inodes's write_file list + */ + spin_lock(&fc->lock); + if (list_empty(&ff->write_entry)) + list_add(&ff->write_entry, &fi->write_files); + spin_unlock(&fc->lock); + } + file_accessed(file); + vma->vm_ops = &fuse_file_vm_ops; return 0; } @@ -940,10 +1227,12 @@ static const struct file_operations fuse_direct_io_file_operations = { static const struct address_space_operations fuse_file_aops = { .readpage = fuse_readpage, + .writepage = fuse_writepage, + .launder_page = fuse_launder_page, .write_begin = fuse_write_begin, .write_end = fuse_write_end, .readpages = fuse_readpages, - .set_page_dirty = fuse_set_page_dirty, + .set_page_dirty = __set_page_dirty_nobuffers, .bmap = fuse_bmap, }; diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index c0481e48d16..4b094fbc9c7 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -15,6 +15,7 @@ #include <linux/mm.h> #include <linux/backing-dev.h> #include <linux/mutex.h> +#include <linux/rwsem.h> /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 @@ -25,6 +26,9 @@ /** Congestion starts at 75% of maximum */ #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100) +/** Bias for fi->writectr, meaning new writepages must not be sent */ +#define FUSE_NOWRITE INT_MIN + /** It could be as large as PATH_MAX, but would that have any uses? */ #define FUSE_NAME_MAX 1024 @@ -73,6 +77,19 @@ struct fuse_inode { /** Files usable in writepage. Protected by fc->lock */ struct list_head write_files; + + /** Writepages pending on truncate or fsync */ + struct list_head queued_writes; + + /** Number of sent writes, a negative bias (FUSE_NOWRITE) + * means more writes are blocked */ + int writectr; + + /** Waitq for writepage completion */ + wait_queue_head_t page_waitq; + + /** List of writepage requestst (pending or sent) */ + struct list_head writepages; }; /** FUSE specific file data */ @@ -242,6 +259,12 @@ struct fuse_req { /** File used in the request (or NULL) */ struct fuse_file *ff; + /** Inode used in the request or NULL */ + struct inode *inode; + + /** Link on fi->writepages */ + struct list_head writepages_entry; + /** Request completion callback */ void (*end)(struct fuse_conn *, struct fuse_req *); @@ -504,6 +527,11 @@ void fuse_init_symlink(struct inode *inode); void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, u64 attr_valid, u64 attr_version); +void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr, + u64 attr_valid); + +void fuse_truncate(struct address_space *mapping, loff_t offset); + /** * Initialize the client device */ @@ -522,6 +550,8 @@ void fuse_ctl_cleanup(void); */ struct fuse_req *fuse_request_alloc(void); +struct fuse_req *fuse_request_alloc_nofs(void); + /** * Free a request */ @@ -558,6 +588,8 @@ void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req); */ void request_send_background(struct fuse_conn *fc, struct fuse_req *req); +void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req); + /* Abort all requests */ void fuse_abort_conn(struct fuse_conn *fc); @@ -600,3 +632,8 @@ u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id); int fuse_update_attributes(struct inode *inode, struct kstat *stat, struct file *file, bool *refreshed); + +void fuse_flush_writepages(struct inode *inode); + +void fuse_set_nowrite(struct inode *inode); +void fuse_release_nowrite(struct inode *inode); diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index c4fcfd59cd8..7d01c68852a 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -59,7 +59,11 @@ static struct inode *fuse_alloc_inode(struct super_block *sb) fi->nodeid = 0; fi->nlookup = 0; fi->attr_version = 0; + fi->writectr = 0; INIT_LIST_HEAD(&fi->write_files); + INIT_LIST_HEAD(&fi->queued_writes); + INIT_LIST_HEAD(&fi->writepages); + init_waitqueue_head(&fi->page_waitq); fi->forget_req = fuse_request_alloc(); if (!fi->forget_req) { kmem_cache_free(fuse_inode_cachep, inode); @@ -73,6 +77,7 @@ static void fuse_destroy_inode(struct inode *inode) { struct fuse_inode *fi = get_fuse_inode(inode); BUG_ON(!list_empty(&fi->write_files)); + BUG_ON(!list_empty(&fi->queued_writes)); if (fi->forget_req) fuse_request_free(fi->forget_req); kmem_cache_free(fuse_inode_cachep, inode); @@ -109,7 +114,7 @@ static int fuse_remount_fs(struct super_block *sb, int *flags, char *data) return 0; } -static void fuse_truncate(struct address_space *mapping, loff_t offset) +void fuse_truncate(struct address_space *mapping, loff_t offset) { /* See vmtruncate() */ unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); @@ -117,19 +122,12 @@ static void fuse_truncate(struct address_space *mapping, loff_t offset) unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); } - -void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, - u64 attr_valid, u64 attr_version) +void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr, + u64 attr_valid) { struct fuse_conn *fc = get_fuse_conn(inode); struct fuse_inode *fi = get_fuse_inode(inode); - loff_t oldsize; - spin_lock(&fc->lock); - if (attr_version != 0 && fi->attr_version > attr_version) { - spin_unlock(&fc->lock); - return; - } fi->attr_version = ++fc->attr_version; fi->i_time = attr_valid; @@ -159,6 +157,22 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, fi->orig_i_mode = inode->i_mode; if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS)) inode->i_mode &= ~S_ISVTX; +} + +void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, + u64 attr_valid, u64 attr_version) +{ + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + loff_t oldsize; + + spin_lock(&fc->lock); + if (attr_version != 0 && fi->attr_version > attr_version) { + spin_unlock(&fc->lock); + return; + } + + fuse_change_attributes_common(inode, attr, attr_valid); oldsize = inode->i_size; i_size_write(inode, attr->size); @@ -468,6 +482,8 @@ static struct fuse_conn *new_conn(struct super_block *sb) atomic_set(&fc->num_waiting, 0); fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; fc->bdi.unplug_io_fn = default_unplug_io_fn; + /* fuse does it's own writeback accounting */ + fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB; fc->dev = sb->s_dev; err = bdi_init(&fc->bdi); if (err) @@ -475,6 +491,19 @@ static struct fuse_conn *new_conn(struct super_block *sb) err = bdi_register_dev(&fc->bdi, fc->dev); if (err) goto error_bdi_destroy; + /* + * For a single fuse filesystem use max 1% of dirty + + * writeback threshold. + * + * This gives about 1M of write buffer for memory maps on a + * machine with 1G and 10% dirty_ratio, which should be more + * than enough. + * + * Privileged users can raise it by writing to + * + * /sys/class/bdi/<bdi>/max_ratio + */ + bdi_set_max_ratio(&fc->bdi, 1); fc->reqctr = 0; fc->blocked = 1; fc->attr_version = 1; |