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author | Steven Whitehouse <swhiteho@redhat.com> | 2006-07-03 10:25:08 -0400 |
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committer | Steven Whitehouse <swhiteho@redhat.com> | 2006-07-03 10:25:08 -0400 |
commit | 0a1340c185734a57fbf4775927966ad4a1347b02 (patch) | |
tree | d9ed8f0dd809a7c542a3356601125ea5b5aaa804 /fs/dcache.c | |
parent | af18ddb8864b096e3ed4732e2d4b21c956dcfe3a (diff) | |
parent | 29454dde27d8e340bb1987bad9aa504af7081eba (diff) | |
download | op-kernel-dev-0a1340c185734a57fbf4775927966ad4a1347b02.zip op-kernel-dev-0a1340c185734a57fbf4775927966ad4a1347b02.tar.gz |
Merge rsync://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
include/linux/kernel.h
Diffstat (limited to 'fs/dcache.c')
-rw-r--r-- | fs/dcache.c | 115 |
1 files changed, 64 insertions, 51 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 940d188..c6e3535 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -14,7 +14,6 @@ * the dcache entry is deleted or garbage collected. */ -#include <linux/config.h> #include <linux/syscalls.h> #include <linux/string.h> #include <linux/mm.h> @@ -359,12 +358,13 @@ restart: } /* - * Throw away a dentry - free the inode, dput the parent. - * This requires that the LRU list has already been - * removed. + * Throw away a dentry - free the inode, dput the parent. This requires that + * the LRU list has already been removed. + * * Called with dcache_lock, drops it and then regains. + * Called with dentry->d_lock held, drops it. */ -static inline void prune_one_dentry(struct dentry * dentry) +static void prune_one_dentry(struct dentry * dentry) { struct dentry * parent; @@ -382,6 +382,8 @@ static inline void prune_one_dentry(struct dentry * dentry) /** * prune_dcache - shrink the dcache * @count: number of entries to try and free + * @sb: if given, ignore dentries for other superblocks + * which are being unmounted. * * Shrink the dcache. This is done when we need * more memory, or simply when we need to unmount @@ -392,16 +394,29 @@ static inline void prune_one_dentry(struct dentry * dentry) * all the dentries are in use. */ -static void prune_dcache(int count) +static void prune_dcache(int count, struct super_block *sb) { spin_lock(&dcache_lock); for (; count ; count--) { struct dentry *dentry; struct list_head *tmp; + struct rw_semaphore *s_umount; cond_resched_lock(&dcache_lock); tmp = dentry_unused.prev; + if (sb) { + /* Try to find a dentry for this sb, but don't try + * too hard, if they aren't near the tail they will + * be moved down again soon + */ + int skip = count; + while (skip && tmp != &dentry_unused && + list_entry(tmp, struct dentry, d_lru)->d_sb != sb) { + skip--; + tmp = tmp->prev; + } + } if (tmp == &dentry_unused) break; list_del_init(tmp); @@ -427,7 +442,45 @@ static void prune_dcache(int count) spin_unlock(&dentry->d_lock); continue; } - prune_one_dentry(dentry); + /* + * If the dentry is not DCACHED_REFERENCED, it is time + * to remove it from the dcache, provided the super block is + * NULL (which means we are trying to reclaim memory) + * or this dentry belongs to the same super block that + * we want to shrink. + */ + /* + * If this dentry is for "my" filesystem, then I can prune it + * without taking the s_umount lock (I already hold it). + */ + if (sb && dentry->d_sb == sb) { + prune_one_dentry(dentry); + continue; + } + /* + * ...otherwise we need to be sure this filesystem isn't being + * unmounted, otherwise we could race with + * generic_shutdown_super(), and end up holding a reference to + * an inode while the filesystem is unmounted. + * So we try to get s_umount, and make sure s_root isn't NULL. + * (Take a local copy of s_umount to avoid a use-after-free of + * `dentry'). + */ + s_umount = &dentry->d_sb->s_umount; + if (down_read_trylock(s_umount)) { + if (dentry->d_sb->s_root != NULL) { + prune_one_dentry(dentry); + up_read(s_umount); + continue; + } + up_read(s_umount); + } + spin_unlock(&dentry->d_lock); + /* Cannot remove the first dentry, and it isn't appropriate + * to move it to the head of the list, so give up, and try + * later + */ + break; } spin_unlock(&dcache_lock); } @@ -468,8 +521,7 @@ void shrink_dcache_sb(struct super_block * sb) dentry = list_entry(tmp, struct dentry, d_lru); if (dentry->d_sb != sb) continue; - list_del(tmp); - list_add(tmp, &dentry_unused); + list_move(tmp, &dentry_unused); } /* @@ -584,7 +636,7 @@ resume: * of the unused list for prune_dcache */ if (!atomic_read(&dentry->d_count)) { - list_add(&dentry->d_lru, dentry_unused.prev); + list_add_tail(&dentry->d_lru, &dentry_unused); dentry_stat.nr_unused++; found++; } @@ -630,46 +682,7 @@ void shrink_dcache_parent(struct dentry * parent) int found; while ((found = select_parent(parent)) != 0) - prune_dcache(found); -} - -/** - * shrink_dcache_anon - further prune the cache - * @head: head of d_hash list of dentries to prune - * - * Prune the dentries that are anonymous - * - * parsing d_hash list does not hlist_for_each_entry_rcu() as it - * done under dcache_lock. - * - */ -void shrink_dcache_anon(struct hlist_head *head) -{ - struct hlist_node *lp; - int found; - do { - found = 0; - spin_lock(&dcache_lock); - hlist_for_each(lp, head) { - struct dentry *this = hlist_entry(lp, struct dentry, d_hash); - if (!list_empty(&this->d_lru)) { - dentry_stat.nr_unused--; - list_del_init(&this->d_lru); - } - - /* - * move only zero ref count dentries to the end - * of the unused list for prune_dcache - */ - if (!atomic_read(&this->d_count)) { - list_add_tail(&this->d_lru, &dentry_unused); - dentry_stat.nr_unused++; - found++; - } - } - spin_unlock(&dcache_lock); - prune_dcache(found); - } while(found); + prune_dcache(found, parent->d_sb); } /* @@ -689,7 +702,7 @@ static int shrink_dcache_memory(int nr, gfp_t gfp_mask) if (nr) { if (!(gfp_mask & __GFP_FS)) return -1; - prune_dcache(nr); + prune_dcache(nr, NULL); } return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; } |