diff options
| -rw-r--r-- | fs/namei.c | 141 |
1 files changed, 56 insertions, 85 deletions
diff --git a/fs/namei.c b/fs/namei.c index ca9a06a65704..0bebd13e5cb7 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -589,29 +589,6 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd) return dentry; } -static inline struct dentry * -do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd) -{ - int status = d_revalidate(dentry, nd); - if (likely(status > 0)) - return dentry; - if (status == -ECHILD) { - if (nameidata_dentry_drop_rcu(nd, dentry)) - return ERR_PTR(-ECHILD); - return do_revalidate(dentry, nd); - } - if (status < 0) - return ERR_PTR(status); - /* Don't d_invalidate in rcu-walk mode */ - if (nameidata_dentry_drop_rcu(nd, dentry)) - return ERR_PTR(-ECHILD); - if (!d_invalidate(dentry)) { - dput(dentry); - dentry = NULL; - } - return dentry; -} - /* * handle_reval_path - force revalidation of a dentry * @@ -1213,7 +1190,8 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, { struct vfsmount *mnt = nd->path.mnt; struct dentry *dentry, *parent = nd->path.dentry; - struct inode *dir; + int need_reval = 1; + int status = 1; int err; /* @@ -1223,48 +1201,74 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, */ if (nd->flags & LOOKUP_RCU) { unsigned seq; - *inode = nd->inode; dentry = __d_lookup_rcu(parent, name, &seq, inode); - if (!dentry) { - if (nameidata_drop_rcu(nd)) - return -ECHILD; - goto need_lookup; - } + if (!dentry) + goto unlazy; + /* Memory barrier in read_seqcount_begin of child is enough */ if (__read_seqcount_retry(&parent->d_seq, nd->seq)) return -ECHILD; - nd->seq = seq; + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { - dentry = do_revalidate_rcu(dentry, nd); - if (!dentry) - goto need_lookup; - if (IS_ERR(dentry)) - goto fail; - if (!(nd->flags & LOOKUP_RCU)) - goto done; + status = d_revalidate(dentry, nd); + if (unlikely(status <= 0)) { + if (status != -ECHILD) + need_reval = 0; + goto unlazy; + } } path->mnt = mnt; path->dentry = dentry; if (likely(__follow_mount_rcu(nd, path, inode, false))) return 0; - if (nameidata_drop_rcu(nd)) - return -ECHILD; - /* fallthru */ +unlazy: + if (dentry) { + if (nameidata_dentry_drop_rcu(nd, dentry)) + return -ECHILD; + } else { + if (nameidata_drop_rcu(nd)) + return -ECHILD; + } + } else { + dentry = __d_lookup(parent, name); } - dentry = __d_lookup(parent, name); - if (!dentry) - goto need_lookup; -found: - if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { - dentry = do_revalidate(dentry, nd); - if (!dentry) - goto need_lookup; - if (IS_ERR(dentry)) - goto fail; + +retry: + if (unlikely(!dentry)) { + struct inode *dir = parent->d_inode; + BUG_ON(nd->inode != dir); + + mutex_lock(&dir->i_mutex); + dentry = d_lookup(parent, name); + if (likely(!dentry)) { + dentry = d_alloc_and_lookup(parent, name, 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); + } + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) + status = d_revalidate(dentry, nd); + if (unlikely(status <= 0)) { + if (status < 0) { + dput(dentry); + return status; + } + if (!d_invalidate(dentry)) { + dput(dentry); + dentry = NULL; + need_reval = 1; + goto retry; + } } -done: + path->mnt = mnt; path->dentry = dentry; err = follow_managed(path, nd->flags); @@ -1274,39 +1278,6 @@ done: } *inode = path->dentry->d_inode; return 0; - -need_lookup: - dir = parent->d_inode; - BUG_ON(nd->inode != dir); - - mutex_lock(&dir->i_mutex); - /* - * First re-do the cached lookup just in case it was created - * while we waited for the directory semaphore, or the first - * lookup failed due to an unrelated rename. - * - * This could use version numbering or similar to avoid unnecessary - * cache lookups, but then we'd have to do the first lookup in the - * non-racy way. However in the common case here, everything should - * be hot in cache, so would it be a big win? - */ - dentry = d_lookup(parent, name); - if (likely(!dentry)) { - dentry = d_alloc_and_lookup(parent, name, nd); - mutex_unlock(&dir->i_mutex); - if (IS_ERR(dentry)) - goto fail; - goto done; - } - /* - * Uhhuh! Nasty case: the cache was re-populated while - * we waited on the semaphore. Need to revalidate. - */ - mutex_unlock(&dir->i_mutex); - goto found; - -fail: - return PTR_ERR(dentry); } static inline int may_lookup(struct nameidata *nd) |