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| author | J. Bruce Fields <bfields@redhat.com> | 2014-02-17 17:45:56 -0500 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2014-08-07 14:40:10 -0400 |
| commit | 75a2352d0110960aeee1a28ddc09a55f97c99100 (patch) | |
| tree | 09df0569f40eb0a50a752575fa7991c62b98a76b | |
| parent | 3f70bd51cb4405dc5cf8624292ffa474679fc9c7 (diff) | |
| download | linux-75a2352d0110960aeee1a28ddc09a55f97c99100.tar.gz linux-75a2352d0110960aeee1a28ddc09a55f97c99100.tar.bz2 linux-75a2352d0110960aeee1a28ddc09a55f97c99100.zip | |
dcache: close d_move race in d_splice_alias
d_splice_alias will d_move an IS_ROOT() directory dentry into place if
one exists. This should be safe as long as the dentry remains IS_ROOT,
but I can't see what guarantees that: once we drop the i_lock all we
hold here is the i_mutex on an unrelated parent directory.
Instead copy the logic of d_materialise_unique.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/dcache.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 8bdae36a095f..8c09db9bb2a4 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2676,9 +2676,14 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) new = __d_find_alias(inode, 1); if (new) { BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); + write_seqlock(&rename_lock); + __d_materialise_dentry(dentry, new); + write_sequnlock(&rename_lock); + __d_drop(new); + _d_rehash(new); + spin_unlock(&new->d_lock); spin_unlock(&inode->i_lock); security_d_instantiate(new, inode); - d_move(new, dentry); iput(inode); } else { /* already taking inode->i_lock, so d_add() by hand */ |