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authorAl Viro <viro@zeniv.linux.org.uk>2018-05-10 22:59:45 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2018-05-21 14:30:10 -0400
commit9c3e9025a3f7ed25c99a0add8af65431c8043800 (patch)
treed8f892f5750d1aea00dcef9d9f7ea1719f11a6ce
parent7b745a4e4051e1bbce40e0b1c2cf636c70583aa4 (diff)
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cachefiles: vfs_mkdir() might succeed leaving dentry negative unhashed
That can (and does, on some filesystems) happen - ->mkdir() (and thus vfs_mkdir()) can legitimately leave its argument negative and just unhash it, counting upon the lookup to pick the object we'd created next time we try to look at that name. Some vfs_mkdir() callers forget about that possibility... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/cachefiles/namei.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 0daa1e3fe0df..ab0bbe93b398 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -572,6 +572,11 @@ lookup_again:
if (ret < 0)
goto create_error;
+ if (unlikely(d_unhashed(next))) {
+ dput(next);
+ inode_unlock(d_inode(dir));
+ goto lookup_again;
+ }
ASSERT(d_backing_inode(next));
_debug("mkdir -> %p{%p{ino=%lu}}",
@@ -764,6 +769,7 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
/* search the current directory for the element name */
inode_lock(d_inode(dir));
+retry:
start = jiffies;
subdir = lookup_one_len(dirname, dir, strlen(dirname));
cachefiles_hist(cachefiles_lookup_histogram, start);
@@ -793,6 +799,10 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
if (ret < 0)
goto mkdir_error;
+ if (unlikely(d_unhashed(subdir))) {
+ dput(subdir);
+ goto retry;
+ }
ASSERT(d_backing_inode(subdir));
_debug("mkdir -> %p{%p{ino=%lu}}",