From 3049cfe24ef3872ba74f90630356722cf988b80d Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 10 Oct 2010 05:36:25 -0400 Subject: fs: split __shrink_dcache_sb Currently __shrink_dcache_sb has an extremly awkward calling convention because it tries to please very different callers. Split out the main loop into a shrink_dentry_list helper, which gets called directly from shrink_dcache_sb for the cases where all dentries need to be pruned, or from __shrink_dcache_sb for pruning only a certain number of dentries. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/dcache.c | 127 ++++++++++++++++++++++++++++++++---------------------------- 1 file changed, 67 insertions(+), 60 deletions(-) (limited to 'fs/dcache.c') diff --git a/fs/dcache.c b/fs/dcache.c index 1a976d4efbe1..e987ad576a39 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -459,66 +459,20 @@ static void prune_one_dentry(struct dentry * dentry) } } -/* - * Shrink the dentry LRU on a given superblock. - * @sb : superblock to shrink dentry LRU. - * @count: If count is NULL, we prune all dentries on superblock. - * @flags: If flags is non-zero, we need to do special processing based on - * which flags are set. This means we don't need to maintain multiple - * similar copies of this loop. - */ -static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) +static void shrink_dentry_list(struct list_head *list) { - LIST_HEAD(referenced); - LIST_HEAD(tmp); struct dentry *dentry; - int cnt = 0; - BUG_ON(!sb); - BUG_ON((flags & DCACHE_REFERENCED) && count == NULL); - spin_lock(&dcache_lock); - if (count != NULL) - /* called from prune_dcache() and shrink_dcache_parent() */ - cnt = *count; -restart: - if (count == NULL) - list_splice_init(&sb->s_dentry_lru, &tmp); - else { - while (!list_empty(&sb->s_dentry_lru)) { - dentry = list_entry(sb->s_dentry_lru.prev, - struct dentry, d_lru); - BUG_ON(dentry->d_sb != sb); - - spin_lock(&dentry->d_lock); - /* - * If we are honouring the DCACHE_REFERENCED flag and - * the dentry has this flag set, don't free it. Clear - * the flag and put it back on the LRU. - */ - if ((flags & DCACHE_REFERENCED) - && (dentry->d_flags & DCACHE_REFERENCED)) { - dentry->d_flags &= ~DCACHE_REFERENCED; - list_move(&dentry->d_lru, &referenced); - spin_unlock(&dentry->d_lock); - } else { - list_move_tail(&dentry->d_lru, &tmp); - spin_unlock(&dentry->d_lock); - cnt--; - if (!cnt) - break; - } - cond_resched_lock(&dcache_lock); - } - } - while (!list_empty(&tmp)) { - dentry = list_entry(tmp.prev, struct dentry, d_lru); + while (!list_empty(list)) { + dentry = list_entry(list->prev, struct dentry, d_lru); dentry_lru_del_init(dentry); - spin_lock(&dentry->d_lock); + /* * We found an inuse dentry which was not removed from * the LRU because of laziness during lookup. Do not free * it - just keep it off the LRU list. */ + spin_lock(&dentry->d_lock); if (atomic_read(&dentry->d_count)) { spin_unlock(&dentry->d_lock); continue; @@ -527,13 +481,60 @@ restart: /* dentry->d_lock was dropped in prune_one_dentry() */ cond_resched_lock(&dcache_lock); } - if (count == NULL && !list_empty(&sb->s_dentry_lru)) - goto restart; - if (count != NULL) - *count = cnt; +} + +/** + * __shrink_dcache_sb - shrink the dentry LRU on a given superblock + * @sb: superblock to shrink dentry LRU. + * @count: number of entries to prune + * @flags: flags to control the dentry processing + * + * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. + */ +static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) +{ + /* called from prune_dcache() and shrink_dcache_parent() */ + struct dentry *dentry; + LIST_HEAD(referenced); + LIST_HEAD(tmp); + int cnt = *count; + + spin_lock(&dcache_lock); + while (!list_empty(&sb->s_dentry_lru)) { + dentry = list_entry(sb->s_dentry_lru.prev, + struct dentry, d_lru); + BUG_ON(dentry->d_sb != sb); + + /* + * If we are honouring the DCACHE_REFERENCED flag and the + * dentry has this flag set, don't free it. Clear the flag + * and put it back on the LRU. + */ + if (flags & DCACHE_REFERENCED) { + spin_lock(&dentry->d_lock); + if (dentry->d_flags & DCACHE_REFERENCED) { + dentry->d_flags &= ~DCACHE_REFERENCED; + list_move(&dentry->d_lru, &referenced); + spin_unlock(&dentry->d_lock); + cond_resched_lock(&dcache_lock); + continue; + } + spin_unlock(&dentry->d_lock); + } + + list_move_tail(&dentry->d_lru, &tmp); + if (!--cnt) + break; + cond_resched_lock(&dcache_lock); + } + + *count = cnt; + shrink_dentry_list(&tmp); + if (!list_empty(&referenced)) list_splice(&referenced, &sb->s_dentry_lru); spin_unlock(&dcache_lock); + } /** @@ -619,13 +620,19 @@ static void prune_dcache(int count) * shrink_dcache_sb - shrink dcache for a superblock * @sb: superblock * - * Shrink the dcache for the specified super block. This - * is used to free the dcache before unmounting a file - * system + * Shrink the dcache for the specified super block. This is used to free + * the dcache before unmounting a file system. */ -void shrink_dcache_sb(struct super_block * sb) +void shrink_dcache_sb(struct super_block *sb) { - __shrink_dcache_sb(sb, NULL, 0); + LIST_HEAD(tmp); + + spin_lock(&dcache_lock); + while (!list_empty(&sb->s_dentry_lru)) { + list_splice_init(&sb->s_dentry_lru, &tmp); + shrink_dentry_list(&tmp); + } + spin_unlock(&dcache_lock); } EXPORT_SYMBOL(shrink_dcache_sb); -- cgit v1.2.3-59-g8ed1b