diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2014-05-29 17:11:45 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-03-04 02:06:46 +0300 |
| commit | 6179fe3753519bb624d767c02f9b685642cc63df (patch) | |
| tree | e7053f21695ec61b54d4b3f75259e4d4838a35a9 /fs | |
| parent | 286adf77d94e8b57a620e6cdbdcc72d99d8609b3 (diff) | |
| download | linux-6179fe3753519bb624d767c02f9b685642cc63df.tar.xz | |
dealing with the rest of shrink_dentry_list() livelock
commit b2b80195d8829921506880f6dccd21cabd163d0d upstream.
We have the same problem with ->d_lock order in the inner loop, where
we are dropping references to ancestors. Same solution, basically -
instead of using dentry_kill() we use lock_parent() (introduced in the
previous commit) to get that lock in a safe way, recheck ->d_count
(in case if lock_parent() has ended up dropping and retaking ->d_lock
and somebody managed to grab a reference during that window), trylock
the inode->i_lock and use __dentry_kill() to do the rest.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/dcache.c | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index d30c45e7b819..9c9a3cd16411 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -886,8 +886,26 @@ static void shrink_dentry_list(struct list_head *list) * fragmentation. */ dentry = parent; - while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) - dentry = dentry_kill(dentry, 1); + while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { + parent = lock_parent(dentry); + if (dentry->d_lockref.count != 1) { + dentry->d_lockref.count--; + spin_unlock(&dentry->d_lock); + if (parent) + spin_unlock(&parent->d_lock); + break; + } + inode = dentry->d_inode; /* can't be NULL */ + if (unlikely(!spin_trylock(&inode->i_lock))) { + spin_unlock(&dentry->d_lock); + if (parent) + spin_unlock(&parent->d_lock); + cpu_relax(); + continue; + } + __dentry_kill(dentry); + dentry = parent; + } } } |