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authorAmir Goldstein <amir73il@gmail.com>2018-01-14 18:35:40 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2018-01-19 13:54:33 +0100
commit31747eda41ef3c30c09c5c096b380bf54013746a (patch)
treee21a2defe26df4c86b2ea2a5d0ed58e0ba77e975 /fs/overlayfs/util.c
parenta8750ddca918032d6349adbf9a4b6555e7db20da (diff)
downloadlinux-31747eda41ef3c30c09c5c096b380bf54013746a.tar.bz2
ovl: hash directory inodes for fsnotify
fsnotify pins a watched directory inode in cache, but if directory dentry is released, new lookup will allocate a new dentry and a new inode. Directory events will be notified on the new inode, while fsnotify listener is watching the old pinned inode. Hash all directory inodes to reuse the pinned inode on lookup. Pure upper dirs are hashes by real upper inode, merge and lower dirs are hashed by real lower inode. The reference to lower inode was being held by the lower dentry object in the overlay dentry (oe->lowerstack[0]). Releasing the overlay dentry may drop lower inode refcount to zero. Add a refcount on behalf of the overlay inode to prevent that. As a by-product, hashing directory inodes also detects multiple redirected dirs to the same lower dir and uncovered redirected dir target on and returns -ESTALE on lookup. The reported issue dates back to initial version of overlayfs, but this patch depends on ovl_inode code that was introduced in kernel v4.13. Cc: <stable@vger.kernel.org> #v4.13 Reported-by: Niklas Cassel <niklas.cassel@axis.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Tested-by: Niklas Cassel <niklas.cassel@axis.com>
Diffstat (limited to 'fs/overlayfs/util.c')
-rw-r--r--fs/overlayfs/util.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index d6bb1c9f5e7a..06119f34a69d 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -257,7 +257,7 @@ void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
if (upperdentry)
OVL_I(inode)->__upperdentry = upperdentry;
if (lowerdentry)
- OVL_I(inode)->lower = d_inode(lowerdentry);
+ OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);
}
@@ -273,7 +273,7 @@ void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
*/
smp_wmb();
OVL_I(inode)->__upperdentry = upperdentry;
- if (!S_ISDIR(upperinode->i_mode) && inode_unhashed(inode)) {
+ if (inode_unhashed(inode)) {
inode->i_private = upperinode;
__insert_inode_hash(inode, (unsigned long) upperinode);
}