| Date | Fri, 30 Mar 2012 12:50:29 -0700 | From | Greg KH <> | Subject | [ 116/149] vfs: fix d_ancestor() case in d_materialize_unique |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Michel Lespinasse <walken@google.com>
commit b18dafc86bb879d2f38a1743985d7ceb283c2f4d upstream.
In d_materialise_unique() there are 3 subcases to the 'aliased dentry' case; in two subcases the inode i_lock is properly released but this does not occur in the -ELOOP subcase.
This seems to have been introduced by commit 1836750115f2 ("fix loop checks in d_materialise_unique()").
Signed-off-by: Michel Lespinasse <walken@google.com> [ Added a comment, and moved the unlock to where we generate the -ELOOP, which seems to be more natural.
You probably can't actually trigger this without a buggy network file server - d_materialize_unique() is for finding aliases on non-local filesystems, and the d_ancestor() case is for a hardlinked directory loop.
But we should be robust in the case of such buggy servers anyway. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/dcache.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/dcache.c +++ b/fs/dcache.c @@ -2357,6 +2357,7 @@ struct dentry *d_materialise_unique(stru if (d_ancestor(alias, dentry)) { /* Check for loops */ actual = ERR_PTR(-ELOOP); + spin_unlock(&inode->i_lock); } else if (IS_ROOT(alias)) { /* Is this an anonymous mountpoint that we * could splice into our tree? */ @@ -2366,7 +2367,7 @@ struct dentry *d_materialise_unique(stru goto found; } else { /* Nope, but we must(!) avoid directory - * aliasing */ + * aliasing. This drops inode->i_lock */ actual = __d_unalias(inode, dentry, alias); } write_sequnlock(&rename_lock);
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