diff options
Diffstat (limited to 'fs/dcache.c')
| -rw-r--r-- | fs/dcache.c | 119 |
1 files changed, 69 insertions, 50 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index be18598c7fd7..274f13e2f094 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -225,7 +225,7 @@ static void dentry_unlink_inode(struct dentry * dentry) } /* - * dentry_lru_(add|del|move_tail) must be called with d_lock held. + * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held. */ static void dentry_lru_add(struct dentry *dentry) { @@ -245,6 +245,9 @@ static void __dentry_lru_del(struct dentry *dentry) dentry_stat.nr_unused--; } +/* + * Remove a dentry with references from the LRU. + */ static void dentry_lru_del(struct dentry *dentry) { if (!list_empty(&dentry->d_lru)) { @@ -254,6 +257,23 @@ static void dentry_lru_del(struct dentry *dentry) } } +/* + * Remove a dentry that is unreferenced and about to be pruned + * (unhashed and destroyed) from the LRU, and inform the file system. + * This wrapper should be called _prior_ to unhashing a victim dentry. + */ +static void dentry_lru_prune(struct dentry *dentry) +{ + if (!list_empty(&dentry->d_lru)) { + if (dentry->d_flags & DCACHE_OP_PRUNE) + dentry->d_op->d_prune(dentry); + + spin_lock(&dcache_lru_lock); + __dentry_lru_del(dentry); + spin_unlock(&dcache_lru_lock); + } +} + static void dentry_lru_move_tail(struct dentry *dentry) { spin_lock(&dcache_lru_lock); @@ -301,6 +321,27 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) return parent; } +/* + * Unhash a dentry without inserting an RCU walk barrier or checking that + * dentry->d_lock is locked. The caller must take care of that, if + * appropriate. + */ +static void __d_shrink(struct dentry *dentry) +{ + if (!d_unhashed(dentry)) { + struct hlist_bl_head *b; + if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) + b = &dentry->d_sb->s_anon; + else + b = d_hash(dentry->d_parent, dentry->d_name.hash); + + hlist_bl_lock(b); + __hlist_bl_del(&dentry->d_hash); + dentry->d_hash.pprev = NULL; + hlist_bl_unlock(b); + } +} + /** * d_drop - drop a dentry * @dentry: dentry to drop @@ -319,17 +360,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) void __d_drop(struct dentry *dentry) { if (!d_unhashed(dentry)) { - struct hlist_bl_head *b; - if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) - b = &dentry->d_sb->s_anon; - else - b = d_hash(dentry->d_parent, dentry->d_name.hash); - - hlist_bl_lock(b); - __hlist_bl_del(&dentry->d_hash); - dentry->d_hash.pprev = NULL; - hlist_bl_unlock(b); - + __d_shrink(dentry); dentry_rcuwalk_barrier(dentry); } } @@ -392,8 +423,12 @@ relock: if (ref) dentry->d_count--; - /* if dentry was on the d_lru list delete it from there */ - dentry_lru_del(dentry); + /* + * if dentry was on the d_lru list delete it from there. + * inform the fs via d_prune that this dentry is about to be + * unhashed and destroyed. + */ + dentry_lru_prune(dentry); /* if it was on the hash then remove it */ __d_drop(dentry); return d_kill(dentry, parent); @@ -784,6 +819,7 @@ relock: /** * prune_dcache_sb - shrink the dcache + * @sb: superblock * @nr_to_scan: number of entries to try to free * * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is @@ -828,44 +864,28 @@ EXPORT_SYMBOL(shrink_dcache_sb); static void shrink_dcache_for_umount_subtree(struct dentry *dentry) { struct dentry *parent; - unsigned detached = 0; BUG_ON(!IS_ROOT(dentry)); - /* detach this root from the system */ - spin_lock(&dentry->d_lock); - dentry_lru_del(dentry); - __d_drop(dentry); - spin_unlock(&dentry->d_lock); - for (;;) { /* descend to the first leaf in the current subtree */ - while (!list_empty(&dentry->d_subdirs)) { - struct dentry *loop; - - /* this is a branch with children - detach all of them - * from the system in one go */ - spin_lock(&dentry->d_lock); - list_for_each_entry(loop, &dentry->d_subdirs, - d_u.d_child) { - spin_lock_nested(&loop->d_lock, - DENTRY_D_LOCK_NESTED); - dentry_lru_del(loop); - __d_drop(loop); - spin_unlock(&loop->d_lock); - } - spin_unlock(&dentry->d_lock); - - /* move to the first child */ + while (!list_empty(&dentry->d_subdirs)) dentry = list_entry(dentry->d_subdirs.next, struct dentry, d_u.d_child); - } /* consume the dentries from this leaf up through its parents * until we find one with children or run out altogether */ do { struct inode *inode; + /* + * remove the dentry from the lru, and inform + * the fs that this dentry is about to be + * unhashed and destroyed. + */ + dentry_lru_prune(dentry); + __d_shrink(dentry); + if (dentry->d_count != 0) { printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%s}" @@ -886,14 +906,10 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) list_del(&dentry->d_u.d_child); } else { parent = dentry->d_parent; - spin_lock(&parent->d_lock); parent->d_count--; list_del(&dentry->d_u.d_child); - spin_unlock(&parent->d_lock); } - detached++; - inode = dentry->d_inode; if (inode) { dentry->d_inode = NULL; @@ -938,9 +954,7 @@ void shrink_dcache_for_umount(struct super_block *sb) dentry = sb->s_root; sb->s_root = NULL; - spin_lock(&dentry->d_lock); dentry->d_count--; - spin_unlock(&dentry->d_lock); shrink_dcache_for_umount_subtree(dentry); while (!hlist_bl_empty(&sb->s_anon)) { @@ -1297,6 +1311,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) dentry->d_flags |= DCACHE_OP_REVALIDATE; if (op->d_delete) dentry->d_flags |= DCACHE_OP_DELETE; + if (op->d_prune) + dentry->d_flags |= DCACHE_OP_PRUNE; } EXPORT_SYMBOL(d_set_d_op); @@ -1743,7 +1759,7 @@ seqretry: */ if (read_seqcount_retry(&dentry->d_seq, *seq)) goto seqretry; - if (parent->d_flags & DCACHE_OP_COMPARE) { + if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { if (parent->d_op->d_compare(parent, *inode, dentry, i, tlen, tname, name)) @@ -2138,8 +2154,9 @@ static void dentry_unlock_parents_for_move(struct dentry *dentry, * @target: new dentry * * Update the dcache to reflect the move of a file name. Negative - * dcache entries should not be moved in this way. Caller hold - * rename_lock. + * dcache entries should not be moved in this way. Caller must hold + * rename_lock, the i_mutex of the source and target directories, + * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). */ static void __d_move(struct dentry * dentry, struct dentry * target) { @@ -2202,7 +2219,8 @@ static void __d_move(struct dentry * dentry, struct dentry * target) * @target: new dentry * * Update the dcache to reflect the move of a file name. Negative - * dcache entries should not be moved in this way. + * dcache entries should not be moved in this way. See the locking + * requirements for __d_move. */ void d_move(struct dentry *dentry, struct dentry *target) { @@ -2320,7 +2338,8 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) * @inode: inode to bind to the dentry, to which aliases may be attached * * Introduces an dentry into the tree, substituting an extant disconnected - * root directory alias in its place if there is one + * root directory alias in its place if there is one. Caller must hold the + * i_mutex of the parent directory. */ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) { |