diff options
| -rw-r--r-- | fs/dcache.c | 34 | ||||
| -rw-r--r-- | fs/namei.c | 49 | ||||
| -rw-r--r-- | include/linux/dcache.h | 7 |
3 files changed, 88 insertions, 2 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 6e4ea6d..d390213 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -344,6 +344,24 @@ void d_drop(struct dentry *dentry) EXPORT_SYMBOL(d_drop); /* + * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag + * @dentry: dentry to drop + * + * This is called when we do a lookup on a placeholder dentry that needed to be + * looked up. The dentry should have been hashed in order for it to be found by + * the lookup code, but now needs to be unhashed while we do the actual lookup + * and clear the DCACHE_NEED_LOOKUP flag. + */ +void d_clear_need_lookup(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + __d_drop(dentry); + dentry->d_flags &= ~DCACHE_NEED_LOOKUP; + spin_unlock(&dentry->d_lock); +} +EXPORT_SYMBOL(d_clear_need_lookup); + +/* * Finish off a dentry we've decided to kill. * dentry->d_lock must be held, returns with it unlocked. * If ref is non-zero, then decrement the refcount too. @@ -432,8 +450,13 @@ repeat: if (d_unhashed(dentry)) goto kill_it; - /* Otherwise leave it cached and ensure it's on the LRU */ - dentry->d_flags |= DCACHE_REFERENCED; + /* + * If this dentry needs lookup, don't set the referenced flag so that it + * is more likely to be cleaned up by the dcache shrinker in case of + * memory pressure. + */ + if (!d_need_lookup(dentry)) + dentry->d_flags |= DCACHE_REFERENCED; dentry_lru_add(dentry); dentry->d_count--; @@ -1708,6 +1731,13 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, } /* + * We are going to instantiate this dentry, unhash it and clear the + * lookup flag so we can do that. + */ + if (unlikely(d_need_lookup(found))) + d_clear_need_lookup(found); + + /* * Negative dentry: instantiate it unless the inode is a directory and * already has a dentry. */ @@ -1134,6 +1134,30 @@ static struct dentry *d_alloc_and_lookup(struct dentry *parent, } /* + * We already have a dentry, but require a lookup to be performed on the parent + * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. + * parent->d_inode->i_mutex must be held. d_lookup must have verified that no + * child exists while under i_mutex. + */ +static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, + struct nameidata *nd) +{ + struct inode *inode = parent->d_inode; + struct dentry *old; + + /* Don't create child dentry for a dead directory. */ + if (unlikely(IS_DEADDIR(inode))) + return ERR_PTR(-ENOENT); + + old = inode->i_op->lookup(inode, dentry, nd); + if (unlikely(old)) { + dput(dentry); + dentry = old; + } + return dentry; +} + +/* * It's more convoluted than I'd like it to be, but... it's still fairly * small and for now I'd prefer to have fast path as straight as possible. * It _is_ time-critical. @@ -1172,6 +1196,8 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, goto unlazy; } } + if (unlikely(d_need_lookup(dentry))) + goto unlazy; path->mnt = mnt; path->dentry = dentry; if (unlikely(!__follow_mount_rcu(nd, path, inode))) @@ -1186,6 +1212,10 @@ unlazy: dentry = __d_lookup(parent, name); } + if (dentry && unlikely(d_need_lookup(dentry))) { + dput(dentry); + dentry = NULL; + } retry: if (unlikely(!dentry)) { struct inode *dir = parent->d_inode; @@ -1202,6 +1232,15 @@ retry: /* known good */ need_reval = 0; status = 1; + } else if (unlikely(d_need_lookup(dentry))) { + dentry = d_inode_lookup(parent, dentry, nd); + if (IS_ERR(dentry)) { + mutex_unlock(&dir->i_mutex); + return PTR_ERR(dentry); + } + /* known good */ + need_reval = 0; + status = 1; } mutex_unlock(&dir->i_mutex); } @@ -1683,6 +1722,16 @@ static struct dentry *__lookup_hash(struct qstr *name, */ dentry = d_lookup(base, name); + if (dentry && d_need_lookup(dentry)) { + /* + * __lookup_hash is called with the parent dir's i_mutex already + * held, so we are good to go here. + */ + dentry = d_inode_lookup(base, dentry, nd); + if (IS_ERR(dentry)) + return dentry; + } + if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) dentry = do_revalidate(dentry, nd); diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 19d90a5..5fa5bd3 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -216,6 +216,7 @@ struct dentry_operations { #define DCACHE_MOUNTED 0x10000 /* is a mountpoint */ #define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */ #define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */ +#define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */ #define DCACHE_MANAGED_DENTRY \ (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) @@ -416,6 +417,12 @@ static inline bool d_mountpoint(struct dentry *dentry) return dentry->d_flags & DCACHE_MOUNTED; } +static inline bool d_need_lookup(struct dentry *dentry) +{ + return dentry->d_flags & DCACHE_NEED_LOOKUP; +} + +extern void d_clear_need_lookup(struct dentry *dentry); extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); extern int sysctl_vfs_cache_pressure; |
