From 7eaebe7d503c3ef240ac7b3efc5433fe647c0298 Mon Sep 17 00:00:00 2001 From: Huang Weiyi Date: Wed, 21 Jan 2009 10:49:16 -0500 Subject: Btrfs: removed unused #include 's Removed unused #include 's in btrfs Signed-off-by: Huang Weiyi Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 1 - 1 file changed, 1 deletion(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index e086d407f1f..c9446d4840e 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -9,7 +9,6 @@ #include #include #include -#include #include #include #include "extent_io.h" -- cgit v1.2.3-70-g09d2 From 1506fcc8189cdd4b95e06df7845a09f18b4526a6 Mon Sep 17 00:00:00 2001 From: Yehuda Sadeh Date: Wed, 21 Jan 2009 14:39:14 -0500 Subject: Btrfs: fiemap support Now that bmap support is gone, this is the only way to get extent mappings for userland. These are still not valid for IO, but they can tell us if a file has holes or how much fragmentation there is. Signed-off-by: Yehuda Sadeh --- fs/btrfs/extent_io.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/extent_io.h | 2 ++ fs/btrfs/inode.c | 7 ++++ 3 files changed, 101 insertions(+) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index c9446d4840e..a3b0676403f 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2854,6 +2854,98 @@ out: return sector; } +int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, + __u64 start, __u64 len, get_extent_t *get_extent) +{ + int ret; + u64 off = start; + u64 max = start + len; + u32 flags = 0; + u64 disko = 0; + struct extent_map *em = NULL; + int end = 0; + u64 em_start = 0, em_len = 0; + unsigned long emflags; + ret = 0; + + if (len == 0) + return -EINVAL; + + lock_extent(&BTRFS_I(inode)->io_tree, start, start + len, + GFP_NOFS); + em = get_extent(inode, NULL, 0, off, max - off, 0); + if (!em) + goto out; + if (IS_ERR(em)) { + ret = PTR_ERR(em); + goto out; + } + while (!end) { + off = em->start + em->len; + if (off >= max) + end = 1; + + em_start = em->start; + em_len = em->len; + + disko = 0; + flags = 0; + + switch (em->block_start) { + case EXTENT_MAP_LAST_BYTE: + end = 1; + flags |= FIEMAP_EXTENT_LAST; + break; + case EXTENT_MAP_HOLE: + flags |= FIEMAP_EXTENT_UNWRITTEN; + break; + case EXTENT_MAP_INLINE: + flags |= (FIEMAP_EXTENT_DATA_INLINE | + FIEMAP_EXTENT_NOT_ALIGNED); + break; + case EXTENT_MAP_DELALLOC: + flags |= (FIEMAP_EXTENT_DELALLOC | + FIEMAP_EXTENT_UNKNOWN); + break; + default: + disko = em->block_start; + break; + } + if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) + flags |= FIEMAP_EXTENT_ENCODED; + + emflags = em->flags; + free_extent_map(em); + em = NULL; + + if (!end) { + em = get_extent(inode, NULL, 0, off, max - off, 0); + if (!em) + goto out; + if (IS_ERR(em)) { + ret = PTR_ERR(em); + goto out; + } + emflags = em->flags; + } + if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) { + flags |= FIEMAP_EXTENT_LAST; + end = 1; + } + + ret = fiemap_fill_next_extent(fieinfo, em_start, disko, + em_len, flags); + if (ret) + goto out_free; + } +out_free: + free_extent_map(em); +out: + unlock_extent(&BTRFS_I(inode)->io_tree, start, start + len, + GFP_NOFS); + return ret; +} + static inline struct page *extent_buffer_page(struct extent_buffer *eb, unsigned long i) { diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index c5b483a7913..e80c6d96b31 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -193,6 +193,8 @@ int extent_commit_write(struct extent_io_tree *tree, unsigned from, unsigned to); sector_t extent_bmap(struct address_space *mapping, sector_t iblock, get_extent_t *get_extent); +int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, + __u64 start, __u64 len, get_extent_t *get_extent); int set_range_dirty(struct extent_io_tree *tree, u64 start, u64 end); int set_state_private(struct extent_io_tree *tree, u64 start, u64 private); int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 2e25d698bab..288c2cdc754 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4156,6 +4156,12 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb, return -EINVAL; } +static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, + __u64 start, __u64 len) +{ + return extent_fiemap(inode, fieinfo, start, len, btrfs_get_extent); +} + int btrfs_readpage(struct file *file, struct page *page) { struct extent_io_tree *tree; @@ -5021,6 +5027,7 @@ static struct inode_operations btrfs_file_inode_operations = { .removexattr = btrfs_removexattr, .permission = btrfs_permission, .fallocate = btrfs_fallocate, + .fiemap = btrfs_fiemap, }; static struct inode_operations btrfs_special_inode_operations = { .getattr = btrfs_getattr, -- cgit v1.2.3-70-g09d2 From 3935127c50c84106d654ef14962cff28c660bc62 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:24:05 -0500 Subject: Btrfs: disable leak debugging checks in extent_io.c extent_io.c has debugging code to report and free leaked extent_state and extent_buffer objects at rmmod time. This helps track down leaks and it saves you from rebooting just to properly remove the kmem_cache object. But, the code runs under a fairly expensive spinlock and the checks to see if it is currently enabled are not entirely consistent. Some use #ifdef and some #if. This changes everything to #if and disables the leak checking. Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index a3b0676403f..2ea7f052722 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -30,7 +30,7 @@ static LIST_HEAD(buffers); static LIST_HEAD(states); #define LEAK_DEBUG 0 -#ifdef LEAK_DEBUG +#if LEAK_DEBUG static DEFINE_SPINLOCK(leak_lock); #endif @@ -119,7 +119,7 @@ void extent_io_tree_init(struct extent_io_tree *tree, static struct extent_state *alloc_extent_state(gfp_t mask) { struct extent_state *state; -#ifdef LEAK_DEBUG +#if LEAK_DEBUG unsigned long flags; #endif @@ -129,7 +129,7 @@ static struct extent_state *alloc_extent_state(gfp_t mask) state->state = 0; state->private = 0; state->tree = NULL; -#ifdef LEAK_DEBUG +#if LEAK_DEBUG spin_lock_irqsave(&leak_lock, flags); list_add(&state->leak_list, &states); spin_unlock_irqrestore(&leak_lock, flags); @@ -144,11 +144,11 @@ static void free_extent_state(struct extent_state *state) if (!state) return; if (atomic_dec_and_test(&state->refs)) { -#ifdef LEAK_DEBUG +#if LEAK_DEBUG unsigned long flags; #endif WARN_ON(state->tree); -#ifdef LEAK_DEBUG +#if LEAK_DEBUG spin_lock_irqsave(&leak_lock, flags); list_del(&state->leak_list); spin_unlock_irqrestore(&leak_lock, flags); @@ -2983,7 +2983,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, gfp_t mask) { struct extent_buffer *eb = NULL; -#ifdef LEAK_DEBUG +#if LEAK_DEBUG unsigned long flags; #endif @@ -2991,7 +2991,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, eb->start = start; eb->len = len; mutex_init(&eb->mutex); -#ifdef LEAK_DEBUG +#if LEAK_DEBUG spin_lock_irqsave(&leak_lock, flags); list_add(&eb->leak_list, &buffers); spin_unlock_irqrestore(&leak_lock, flags); @@ -3003,7 +3003,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, static void __free_extent_buffer(struct extent_buffer *eb) { -#ifdef LEAK_DEBUG +#if LEAK_DEBUG unsigned long flags; spin_lock_irqsave(&leak_lock, flags); list_del(&eb->leak_list); -- cgit v1.2.3-70-g09d2 From b4ce94de9b4d64e8ab3cf155d13653c666e22b9b Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:25:08 -0500 Subject: Btrfs: Change btree locking to use explicit blocking points Most of the btrfs metadata operations can be protected by a spinlock, but some operations still need to schedule. So far, btrfs has been using a mutex along with a trylock loop, most of the time it is able to avoid going for the full mutex, so the trylock loop is a big performance gain. This commit is step one for getting rid of the blocking locks entirely. btrfs_tree_lock takes a spinlock, and the code explicitly switches to a blocking lock when it starts an operation that can schedule. We'll be able get rid of the blocking locks in smaller pieces over time. Tracing allows us to find the most common cause of blocking, so we can start with the hot spots first. The basic idea is: btrfs_tree_lock() returns with the spin lock held btrfs_set_lock_blocking() sets the EXTENT_BUFFER_BLOCKING bit in the extent buffer flags, and then drops the spin lock. The buffer is still considered locked by all of the btrfs code. If btrfs_tree_lock gets the spinlock but finds the blocking bit set, it drops the spin lock and waits on a wait queue for the blocking bit to go away. Much of the code that needs to set the blocking bit finishes without actually blocking a good percentage of the time. So, an adaptive spin is still used against the blocking bit to avoid very high context switch rates. btrfs_clear_lock_blocking() clears the blocking bit and returns with the spinlock held again. btrfs_tree_unlock() can be called on either blocking or spinning locks, it does the right thing based on the blocking bit. ctree.c has a helper function to set/clear all the locked buffers in a path as blocking. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 234 +++++++++++++++++++++++++++++++++++++++++++++++-- fs/btrfs/ctree.h | 4 + fs/btrfs/disk-io.c | 10 ++- fs/btrfs/extent-tree.c | 5 ++ fs/btrfs/extent_io.c | 18 ++-- fs/btrfs/extent_io.h | 16 +++- fs/btrfs/inode.c | 3 + fs/btrfs/locking.c | 208 +++++++++++++++++++++++++++++++++++++++---- fs/btrfs/locking.h | 6 ++ fs/btrfs/tree-defrag.c | 1 + fs/btrfs/tree-log.c | 4 + 11 files changed, 470 insertions(+), 39 deletions(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 3b6e35aafc9..3af777357ac 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -54,6 +54,31 @@ struct btrfs_path *btrfs_alloc_path(void) return path; } +/* + * set all locked nodes in the path to blocking locks. This should + * be done before scheduling + */ +noinline void btrfs_set_path_blocking(struct btrfs_path *p) +{ + int i; + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + if (p->nodes[i] && p->locks[i]) + btrfs_set_lock_blocking(p->nodes[i]); + } +} + +/* + * reset all the locked nodes in the patch to spinning locks. + */ +noinline void btrfs_clear_path_blocking(struct btrfs_path *p) +{ + int i; + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + if (p->nodes[i] && p->locks[i]) + btrfs_clear_lock_blocking(p->nodes[i]); + } +} + /* this also releases the path */ void btrfs_free_path(struct btrfs_path *p) { @@ -272,6 +297,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, if (IS_ERR(cow)) return PTR_ERR(cow); + /* cow is set to blocking by btrfs_init_new_buffer */ + copy_extent_buffer(cow, buf, 0, 0, cow->len); btrfs_set_header_bytenr(cow, cow->start); btrfs_set_header_generation(cow, trans->transid); @@ -397,6 +424,11 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, } search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1); + + if (parent) + btrfs_set_lock_blocking(parent); + btrfs_set_lock_blocking(buf); + ret = __btrfs_cow_block(trans, root, buf, parent, parent_slot, cow_ret, search_start, 0, prealloc_dest); @@ -502,6 +534,8 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans, if (parent_nritems == 1) return 0; + btrfs_set_lock_blocking(parent); + for (i = start_slot; i < end_slot; i++) { int close = 1; @@ -562,6 +596,7 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans, search_start = last_block; btrfs_tree_lock(cur); + btrfs_set_lock_blocking(cur); err = __btrfs_cow_block(trans, root, cur, parent, i, &cur, search_start, min(16 * blocksize, @@ -860,6 +895,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, return 0; mid = path->nodes[level]; + WARN_ON(!path->locks[level]); WARN_ON(btrfs_header_generation(mid) != trans->transid); @@ -882,6 +918,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, /* promote the child to a root */ child = read_node_slot(root, mid, 0); btrfs_tree_lock(child); + btrfs_set_lock_blocking(child); BUG_ON(!child); ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0); BUG_ON(ret); @@ -898,6 +935,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, add_root_to_dirty_list(root); btrfs_tree_unlock(child); + path->locks[level] = 0; path->nodes[level] = NULL; clean_tree_block(trans, root, mid); @@ -922,6 +960,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, left = read_node_slot(root, parent, pslot - 1); if (left) { btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); wret = btrfs_cow_block(trans, root, left, parent, pslot - 1, &left, 0); if (wret) { @@ -932,6 +971,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, right = read_node_slot(root, parent, pslot + 1); if (right) { btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); wret = btrfs_cow_block(trans, root, right, parent, pslot + 1, &right, 0); if (wret) { @@ -1107,6 +1147,8 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, u32 left_nr; btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + left_nr = btrfs_header_nritems(left); if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { wret = 1; @@ -1153,7 +1195,10 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, */ if (right) { u32 right_nr; + btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + right_nr = btrfs_header_nritems(right); if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { wret = 1; @@ -1264,6 +1309,68 @@ static noinline void reada_for_search(struct btrfs_root *root, } } +/* + * returns -EAGAIN if it had to drop the path, or zero if everything was in + * cache + */ +static noinline int reada_for_balance(struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + int slot; + int nritems; + struct extent_buffer *parent; + struct extent_buffer *eb; + u64 gen; + u64 block1 = 0; + u64 block2 = 0; + int ret = 0; + int blocksize; + + parent = path->nodes[level - 1]; + if (!parent) + return 0; + + nritems = btrfs_header_nritems(parent); + slot = path->slots[level]; + blocksize = btrfs_level_size(root, level); + + if (slot > 0) { + block1 = btrfs_node_blockptr(parent, slot - 1); + gen = btrfs_node_ptr_generation(parent, slot - 1); + eb = btrfs_find_tree_block(root, block1, blocksize); + if (eb && btrfs_buffer_uptodate(eb, gen)) + block1 = 0; + free_extent_buffer(eb); + } + if (slot < nritems) { + block2 = btrfs_node_blockptr(parent, slot + 1); + gen = btrfs_node_ptr_generation(parent, slot + 1); + eb = btrfs_find_tree_block(root, block2, blocksize); + if (eb && btrfs_buffer_uptodate(eb, gen)) + block2 = 0; + free_extent_buffer(eb); + } + if (block1 || block2) { + ret = -EAGAIN; + btrfs_release_path(root, path); + if (block1) + readahead_tree_block(root, block1, blocksize, 0); + if (block2) + readahead_tree_block(root, block2, blocksize, 0); + + if (block1) { + eb = read_tree_block(root, block1, blocksize, 0); + free_extent_buffer(eb); + } + if (block1) { + eb = read_tree_block(root, block2, blocksize, 0); + free_extent_buffer(eb); + } + } + return ret; +} + + /* * when we walk down the tree, it is usually safe to unlock the higher layers * in the tree. The exceptions are when our path goes through slot 0, because @@ -1314,6 +1421,32 @@ static noinline void unlock_up(struct btrfs_path *path, int level, } } +/* + * This releases any locks held in the path starting at level and + * going all the way up to the root. + * + * btrfs_search_slot will keep the lock held on higher nodes in a few + * corner cases, such as COW of the block at slot zero in the node. This + * ignores those rules, and it should only be called when there are no + * more updates to be done higher up in the tree. + */ +noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) +{ + int i; + + if (path->keep_locks || path->lowest_level) + return; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + if (!path->nodes[i]) + break; + if (!path->locks[i]) + break; + btrfs_tree_unlock(path->nodes[i]); + path->locks[i] = 0; + } +} + /* * look for key in the tree. path is filled in with nodes along the way * if key is found, we return zero and you can find the item in the leaf @@ -1385,6 +1518,7 @@ again: */ if (prealloc_block.objectid && prealloc_block.offset != b->len) { + btrfs_set_path_blocking(p); btrfs_free_reserved_extent(root, prealloc_block.objectid, prealloc_block.offset); @@ -1409,6 +1543,8 @@ again: goto again; } + btrfs_set_path_blocking(p); + wret = btrfs_cow_block(trans, root, b, p->nodes[level + 1], p->slots[level + 1], @@ -1430,6 +1566,22 @@ cow_done: if (!p->skip_locking) p->locks[level] = 1; + btrfs_clear_path_blocking(p); + + /* + * we have a lock on b and as long as we aren't changing + * the tree, there is no way to for the items in b to change. + * It is safe to drop the lock on our parent before we + * go through the expensive btree search on b. + * + * If cow is true, then we might be changing slot zero, + * which may require changing the parent. So, we can't + * drop the lock until after we know which slot we're + * operating on. + */ + if (!cow) + btrfs_unlock_up_safe(p, level + 1); + ret = check_block(root, p, level); if (ret) { ret = -1; @@ -1437,6 +1589,7 @@ cow_done: } ret = bin_search(b, key, level, &slot); + if (level != 0) { if (ret && slot > 0) slot -= 1; @@ -1444,7 +1597,16 @@ cow_done: if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= BTRFS_NODEPTRS_PER_BLOCK(root) - 3) { - int sret = split_node(trans, root, p, level); + int sret; + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = split_node(trans, root, p, level); + btrfs_clear_path_blocking(p); + BUG_ON(sret > 0); if (sret) { ret = sret; @@ -1453,8 +1615,16 @@ cow_done: b = p->nodes[level]; slot = p->slots[level]; } else if (ins_len < 0) { - int sret = balance_level(trans, root, p, - level); + int sret; + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = balance_level(trans, root, p, level); + btrfs_clear_path_blocking(p); + if (sret) { ret = sret; goto done; @@ -1488,7 +1658,7 @@ cow_done: * of the btree by dropping locks before * we read. */ - if (level > 1) { + if (level > 0) { btrfs_release_path(NULL, p); if (tmp) free_extent_buffer(tmp); @@ -1503,6 +1673,7 @@ cow_done: free_extent_buffer(tmp); goto again; } else { + btrfs_set_path_blocking(p); if (tmp) free_extent_buffer(tmp); if (should_reada) @@ -1512,14 +1683,29 @@ cow_done: b = read_node_slot(root, b, slot); } } - if (!p->skip_locking) - btrfs_tree_lock(b); + if (!p->skip_locking) { + int lret; + + btrfs_clear_path_blocking(p); + lret = btrfs_try_spin_lock(b); + + if (!lret) { + btrfs_set_path_blocking(p); + btrfs_tree_lock(b); + btrfs_clear_path_blocking(p); + } + } } else { p->slots[level] = slot; if (ins_len > 0 && btrfs_leaf_free_space(root, b) < ins_len) { - int sret = split_leaf(trans, root, key, + int sret; + + btrfs_set_path_blocking(p); + sret = split_leaf(trans, root, key, p, ins_len, ret == 0); + btrfs_clear_path_blocking(p); + BUG_ON(sret > 0); if (sret) { ret = sret; @@ -1533,12 +1719,16 @@ cow_done: } ret = 1; done: + /* + * we don't really know what they plan on doing with the path + * from here on, so for now just mark it as blocking + */ + btrfs_set_path_blocking(p); if (prealloc_block.objectid) { btrfs_free_reserved_extent(root, prealloc_block.objectid, prealloc_block.offset); } - return ret; } @@ -1562,6 +1752,8 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb, 0); BUG_ON(ret); + btrfs_set_lock_blocking(eb); + parent = eb; while (1) { level = btrfs_header_level(parent); @@ -1586,6 +1778,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, eb = read_tree_block(root, bytenr, blocksize, generation); btrfs_tree_lock(eb); + btrfs_set_lock_blocking(eb); } /* @@ -1610,6 +1803,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, eb = read_tree_block(root, bytenr, blocksize, generation); btrfs_tree_lock(eb); + btrfs_set_lock_blocking(eb); } ret = btrfs_cow_block(trans, root, eb, parent, slot, @@ -2156,6 +2350,8 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root right = read_node_slot(root, upper, slot + 1); btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + free_space = btrfs_leaf_free_space(root, right); if (free_space < data_size) goto out_unlock; @@ -2351,6 +2547,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root left = read_node_slot(root, path->nodes[1], slot - 1); btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + free_space = btrfs_leaf_free_space(root, left); if (free_space < data_size) { ret = 1; @@ -2809,6 +3007,12 @@ int btrfs_split_item(struct btrfs_trans_handle *trans, path->keep_locks = 0; BUG_ON(ret); + /* + * make sure any changes to the path from split_leaf leave it + * in a blocking state + */ + btrfs_set_path_blocking(path); + leaf = path->nodes[0]; BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item)); @@ -3338,6 +3542,7 @@ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, BUG(); } out: + btrfs_unlock_up_safe(path, 1); return ret; } @@ -3705,12 +3910,14 @@ find_next_key: */ if (slot >= nritems) { path->slots[level] = slot; + btrfs_set_path_blocking(path); sret = btrfs_find_next_key(root, path, min_key, level, cache_only, min_trans); if (sret == 0) { btrfs_release_path(root, path); goto again; } else { + btrfs_clear_path_blocking(path); goto out; } } @@ -3722,16 +3929,20 @@ find_next_key: unlock_up(path, level, 1); goto out; } + btrfs_set_path_blocking(path); cur = read_node_slot(root, cur, slot); btrfs_tree_lock(cur); + path->locks[level - 1] = 1; path->nodes[level - 1] = cur; unlock_up(path, level, 1); + btrfs_clear_path_blocking(path); } out: if (ret == 0) memcpy(min_key, &found_key, sizeof(found_key)); + btrfs_set_path_blocking(path); return ret; } @@ -3827,6 +4038,7 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) if (ret < 0) return ret; + btrfs_set_path_blocking(path); nritems = btrfs_header_nritems(path->nodes[0]); /* * by releasing the path above we dropped all our locks. A balance @@ -3857,6 +4069,7 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) free_extent_buffer(next); } + /* the path was set to blocking above */ if (level == 1 && (path->locks[1] || path->skip_locking) && path->reada) reada_for_search(root, path, level, slot, 0); @@ -3865,6 +4078,7 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) if (!path->skip_locking) { WARN_ON(!btrfs_tree_locked(c)); btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); } break; } @@ -3881,12 +4095,15 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) path->locks[level] = 1; if (!level) break; + + btrfs_set_path_blocking(path); if (level == 1 && path->locks[1] && path->reada) reada_for_search(root, path, level, slot, 0); next = read_node_slot(root, next, 0); if (!path->skip_locking) { WARN_ON(!btrfs_tree_locked(path->nodes[level])); btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); } } done: @@ -3911,6 +4128,7 @@ int btrfs_previous_item(struct btrfs_root *root, while (1) { if (path->slots[0] == 0) { + btrfs_set_path_blocking(path); ret = btrfs_prev_leaf(root, path); if (ret != 0) return ret; diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f2b8d26b047..531db112c8b 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1835,6 +1835,10 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p); struct btrfs_path *btrfs_alloc_path(void); void btrfs_free_path(struct btrfs_path *p); void btrfs_init_path(struct btrfs_path *p); +void btrfs_set_path_blocking(struct btrfs_path *p); +void btrfs_clear_path_blocking(struct btrfs_path *p); +void btrfs_unlock_up_safe(struct btrfs_path *p, int level); + int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int slot, int nr); int btrfs_del_leaf(struct btrfs_trans_handle *trans, diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 549271607c1..5aebddd7119 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -799,7 +799,7 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr, ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid); if (ret == 0) - buf->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags); else WARN_ON(1); return buf; @@ -813,6 +813,10 @@ int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, if (btrfs_header_generation(buf) == root->fs_info->running_transaction->transid) { WARN_ON(!btrfs_tree_locked(buf)); + + /* ugh, clear_extent_buffer_dirty can be expensive */ + btrfs_set_lock_blocking(buf); + clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf); } @@ -2311,6 +2315,8 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf) u64 transid = btrfs_header_generation(buf); struct inode *btree_inode = root->fs_info->btree_inode; + btrfs_set_lock_blocking(buf); + WARN_ON(!btrfs_tree_locked(buf)); if (transid != root->fs_info->generation) { printk(KERN_CRIT "btrfs transid mismatch buffer %llu, " @@ -2353,7 +2359,7 @@ int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid) int ret; ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid); if (ret == 0) - buf->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags); return ret; } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 7a22f2e6ec4..ed1e25d7248 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3407,7 +3407,10 @@ struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans, btrfs_set_header_generation(buf, trans->transid); btrfs_tree_lock(buf); clean_tree_block(trans, root, buf); + + btrfs_set_lock_blocking(buf); btrfs_set_buffer_uptodate(buf); + if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) { set_extent_dirty(&root->dirty_log_pages, buf->start, buf->start + buf->len - 1, GFP_NOFS); @@ -3416,6 +3419,7 @@ struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans, buf->start + buf->len - 1, GFP_NOFS); } trans->blocks_used++; + /* this returns a buffer locked for blocking */ return buf; } @@ -3752,6 +3756,7 @@ static noinline int walk_down_subtree(struct btrfs_trans_handle *trans, next = read_tree_block(root, bytenr, blocksize, ptr_gen); btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); ret = btrfs_lookup_extent_ref(trans, root, bytenr, blocksize, &refs); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 2ea7f052722..dd5df53e045 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2990,7 +2990,9 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, eb = kmem_cache_zalloc(extent_buffer_cache, mask); eb->start = start; eb->len = len; - mutex_init(&eb->mutex); + spin_lock_init(&eb->lock); + init_waitqueue_head(&eb->lock_wq); + #if LEAK_DEBUG spin_lock_irqsave(&leak_lock, flags); list_add(&eb->leak_list, &buffers); @@ -3071,8 +3073,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, unlock_page(p); } if (uptodate) - eb->flags |= EXTENT_UPTODATE; - eb->flags |= EXTENT_BUFFER_FILLED; + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); spin_lock(&tree->buffer_lock); exists = buffer_tree_insert(tree, start, &eb->rb_node); @@ -3226,7 +3227,7 @@ int clear_extent_buffer_uptodate(struct extent_io_tree *tree, unsigned long num_pages; num_pages = num_extent_pages(eb->start, eb->len); - eb->flags &= ~EXTENT_UPTODATE; + clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, GFP_NOFS); @@ -3297,7 +3298,7 @@ int extent_buffer_uptodate(struct extent_io_tree *tree, struct page *page; int pg_uptodate = 1; - if (eb->flags & EXTENT_UPTODATE) + if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 1; ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1, @@ -3333,7 +3334,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, struct bio *bio = NULL; unsigned long bio_flags = 0; - if (eb->flags & EXTENT_UPTODATE) + if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0; if (test_range_bit(tree, eb->start, eb->start + eb->len - 1, @@ -3364,7 +3365,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, } if (all_uptodate) { if (start_i == 0) - eb->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); goto unlock_exit; } @@ -3400,7 +3401,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, } if (!ret) - eb->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); return ret; unlock_exit: @@ -3497,7 +3498,6 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start, unmap_extent_buffer(eb, eb->map_token, km); eb->map_token = NULL; save = 1; - WARN_ON(!mutex_is_locked(&eb->mutex)); } err = map_private_extent_buffer(eb, start, min_len, token, map, map_start, map_len, km); diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index e80c6d96b31..1f9df88afbf 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -22,6 +22,10 @@ /* flags for bio submission */ #define EXTENT_BIO_COMPRESSED 1 +/* these are bit numbers for test/set bit */ +#define EXTENT_BUFFER_UPTODATE 0 +#define EXTENT_BUFFER_BLOCKING 1 + /* * page->private values. Every page that is controlled by the extent * map has page->private set to one. @@ -95,11 +99,19 @@ struct extent_buffer { unsigned long map_start; unsigned long map_len; struct page *first_page; + unsigned long bflags; atomic_t refs; - int flags; struct list_head leak_list; struct rb_node rb_node; - struct mutex mutex; + + /* the spinlock is used to protect most operations */ + spinlock_t lock; + + /* + * when we keep the lock held while blocking, waiters go onto + * the wq + */ + wait_queue_head_t lock_wq; }; struct extent_map_tree; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4a79e1c5ebd..ebd7d6c37df 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -50,6 +50,7 @@ #include "tree-log.h" #include "ref-cache.h" #include "compression.h" +#include "locking.h" struct btrfs_iget_args { u64 ino; @@ -2021,6 +2022,7 @@ void btrfs_read_locked_inode(struct inode *inode) BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item); alloc_group_block = btrfs_inode_block_group(leaf, inode_item); + BTRFS_I(inode)->block_group = btrfs_find_block_group(root, 0, alloc_group_block, 0); btrfs_free_path(path); @@ -2117,6 +2119,7 @@ noinline int btrfs_update_inode(struct btrfs_trans_handle *trans, goto failed; } + btrfs_unlock_up_safe(path, 1); leaf = path->nodes[0]; inode_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item); diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 39bae7761db..68fd9ccf180 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -26,45 +26,215 @@ #include "locking.h" /* - * locks the per buffer mutex in an extent buffer. This uses adaptive locks - * and the spin is not tuned very extensively. The spinning does make a big - * difference in almost every workload, but spinning for the right amount of - * time needs some help. - * - * In general, we want to spin as long as the lock holder is doing btree - * searches, and we should give up if they are in more expensive code. + * btrfs_header_level() isn't free, so don't call it when lockdep isn't + * on */ +#ifdef CONFIG_DEBUG_LOCK_ALLOC +static inline void spin_nested(struct extent_buffer *eb) +{ + spin_lock_nested(&eb->lock, BTRFS_MAX_LEVEL - btrfs_header_level(eb)); +} +#else +static inline void spin_nested(struct extent_buffer *eb) +{ + spin_lock(&eb->lock); +} +#endif -int btrfs_tree_lock(struct extent_buffer *eb) +/* + * Setting a lock to blocking will drop the spinlock and set the + * flag that forces other procs who want the lock to wait. After + * this you can safely schedule with the lock held. + */ +void btrfs_set_lock_blocking(struct extent_buffer *eb) { - int i; + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) { + set_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags); + spin_unlock(&eb->lock); + } + /* exit with the spin lock released and the bit set */ +} - if (mutex_trylock(&eb->mutex)) - return 0; +/* + * clearing the blocking flag will take the spinlock again. + * After this you can't safely schedule + */ +void btrfs_clear_lock_blocking(struct extent_buffer *eb) +{ + if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) { + spin_nested(eb); + clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags); + smp_mb__after_clear_bit(); + } + /* exit with the spin lock held */ +} + +/* + * unfortunately, many of the places that currently set a lock to blocking + * don't end up blocking for every long, and often they don't block + * at all. For a dbench 50 run, if we don't spin one the blocking bit + * at all, the context switch rate can jump up to 400,000/sec or more. + * + * So, we're still stuck with this crummy spin on the blocking bit, + * at least until the most common causes of the short blocks + * can be dealt with. + */ +static int btrfs_spin_on_block(struct extent_buffer *eb) +{ + int i; for (i = 0; i < 512; i++) { cpu_relax(); - if (mutex_trylock(&eb->mutex)) + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + return 1; + if (need_resched()) + break; + } + return 0; +} + +/* + * This is somewhat different from trylock. It will take the + * spinlock but if it finds the lock is set to blocking, it will + * return without the lock held. + * + * returns 1 if it was able to take the lock and zero otherwise + * + * After this call, scheduling is not safe without first calling + * btrfs_set_lock_blocking() + */ +int btrfs_try_spin_lock(struct extent_buffer *eb) +{ + int i; + + spin_nested(eb); + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + return 1; + spin_unlock(&eb->lock); + + /* spin for a bit on the BLOCKING flag */ + for (i = 0; i < 2; i++) { + if (!btrfs_spin_on_block(eb)) + break; + + spin_nested(eb); + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + return 1; + spin_unlock(&eb->lock); + } + return 0; +} + +/* + * the autoremove wake function will return 0 if it tried to wake up + * a process that was already awake, which means that process won't + * count as an exclusive wakeup. The waitq code will continue waking + * procs until it finds one that was actually sleeping. + * + * For btrfs, this isn't quite what we want. We want a single proc + * to be notified that the lock is ready for taking. If that proc + * already happen to be awake, great, it will loop around and try for + * the lock. + * + * So, btrfs_wake_function always returns 1, even when the proc that we + * tried to wake up was already awake. + */ +static int btrfs_wake_function(wait_queue_t *wait, unsigned mode, + int sync, void *key) +{ + autoremove_wake_function(wait, mode, sync, key); + return 1; +} + +/* + * returns with the extent buffer spinlocked. + * + * This will spin and/or wait as required to take the lock, and then + * return with the spinlock held. + * + * After this call, scheduling is not safe without first calling + * btrfs_set_lock_blocking() + */ +int btrfs_tree_lock(struct extent_buffer *eb) +{ + DEFINE_WAIT(wait); + wait.func = btrfs_wake_function; + + while(1) { + spin_nested(eb); + + /* nobody is blocking, exit with the spinlock held */ + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) return 0; + + /* + * we have the spinlock, but the real owner is blocking. + * wait for them + */ + spin_unlock(&eb->lock); + + /* + * spin for a bit, and if the blocking flag goes away, + * loop around + */ + if (btrfs_spin_on_block(eb)) + continue; + + prepare_to_wait_exclusive(&eb->lock_wq, &wait, + TASK_UNINTERRUPTIBLE); + + if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + schedule(); + + finish_wait(&eb->lock_wq, &wait); } - cpu_relax(); - mutex_lock_nested(&eb->mutex, BTRFS_MAX_LEVEL - btrfs_header_level(eb)); return 0; } +/* + * Very quick trylock, this does not spin or schedule. It returns + * 1 with the spinlock held if it was able to take the lock, or it + * returns zero if it was unable to take the lock. + * + * After this call, scheduling is not safe without first calling + * btrfs_set_lock_blocking() + */ int btrfs_try_tree_lock(struct extent_buffer *eb) { - return mutex_trylock(&eb->mutex); + if (spin_trylock(&eb->lock)) { + if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) { + /* + * we've got the spinlock, but the real owner is + * blocking. Drop the spinlock and return failure + */ + spin_unlock(&eb->lock); + return 0; + } + return 1; + } + /* someone else has the spinlock giveup */ + return 0; } int btrfs_tree_unlock(struct extent_buffer *eb) { - mutex_unlock(&eb->mutex); + /* + * if we were a blocking owner, we don't have the spinlock held + * just clear the bit and look for waiters + */ + if (test_and_clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + smp_mb__after_clear_bit(); + else + spin_unlock(&eb->lock); + + if (waitqueue_active(&eb->lock_wq)) + wake_up(&eb->lock_wq); return 0; } int btrfs_tree_locked(struct extent_buffer *eb) { - return mutex_is_locked(&eb->mutex); + return test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags) || + spin_is_locked(&eb->lock); } /* @@ -75,12 +245,14 @@ int btrfs_path_lock_waiting(struct btrfs_path *path, int level) { int i; struct extent_buffer *eb; + for (i = level; i <= level + 1 && i < BTRFS_MAX_LEVEL; i++) { eb = path->nodes[i]; if (!eb) break; smp_mb(); - if (!list_empty(&eb->mutex.wait_list)) + if (spin_is_contended(&eb->lock) || + waitqueue_active(&eb->lock_wq)) return 1; } return 0; diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h index bc1faef1251..d92e707f587 100644 --- a/fs/btrfs/locking.h +++ b/fs/btrfs/locking.h @@ -22,6 +22,12 @@ int btrfs_tree_lock(struct extent_buffer *eb); int btrfs_tree_unlock(struct extent_buffer *eb); int btrfs_tree_locked(struct extent_buffer *eb); + int btrfs_try_tree_lock(struct extent_buffer *eb); +int btrfs_try_spin_lock(struct extent_buffer *eb); + int btrfs_path_lock_waiting(struct btrfs_path *path, int level); + +void btrfs_set_lock_blocking(struct extent_buffer *eb); +void btrfs_clear_lock_blocking(struct extent_buffer *eb); #endif diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c index 3e8358c3616..98d25fa4570 100644 --- a/fs/btrfs/tree-defrag.c +++ b/fs/btrfs/tree-defrag.c @@ -74,6 +74,7 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans, u32 nritems; root_node = btrfs_lock_root_node(root); + btrfs_set_lock_blocking(root_node); nritems = btrfs_header_nritems(root_node); root->defrag_max.objectid = 0; /* from above we know this is not a leaf */ diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 4f26f3ed0c8..20794290256 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -1615,6 +1615,7 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans, btrfs_tree_lock(next); clean_tree_block(trans, root, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); @@ -1661,6 +1662,7 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans, next = path->nodes[*level]; btrfs_tree_lock(next); clean_tree_block(trans, root, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); @@ -1718,6 +1720,7 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans, btrfs_tree_lock(next); clean_tree_block(trans, root, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); @@ -1790,6 +1793,7 @@ static int walk_log_tree(struct btrfs_trans_handle *trans, btrfs_tree_lock(next); clean_tree_block(trans, log, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); -- cgit v1.2.3-70-g09d2 From 9b0d3ace33ef225690a86d7130feadb22367f496 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:33:00 -0500 Subject: Btrfs: don't return congestion in write_cache_pages as often On fast devices that go from congested to uncongested very quickly, pdflush is waiting too often in congestion_wait, and the FS is backing off to easily in write_cache_pages. For now, fix this on the btrfs side by only checking congestion after some bios have already gone down. Longer term a real fix is needed for pdflush, but that is a larger project. Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'fs/btrfs/extent_io.c') diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index dd5df53e045..37d43b516b7 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2377,11 +2377,6 @@ static int extent_write_cache_pages(struct extent_io_tree *tree, int scanned = 0; int range_whole = 0; - if (wbc->nonblocking && bdi_write_congested(bdi)) { - wbc->encountered_congestion = 1; - return 0; - } - pagevec_init(&pvec, 0); if (wbc->range_cyclic) { index = mapping->writeback_index; /* Start from prev offset */ -- cgit v1.2.3-70-g09d2