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authorIngo Molnar <mingo@elte.hu>2011-04-01 21:14:04 +0200
committerIngo Molnar <mingo@elte.hu>2011-04-01 21:14:04 +0200
commit5679027e74126e0dfc860869b0e7ceab1dd06318 (patch)
tree9a18b1a2f53be3bad8c9e4db01617fb51f067f64 /fs/xfs/linux-2.6/xfs_sync.c
parentWARN_ON_SMP(): Add comment to explain ({0;}) (diff)
parentrcu: create new rcu_access_index() and use in mce (diff)
downloadlinux-5679027e74126e0dfc860869b0e7ceab1dd06318.tar.xz
linux-5679027e74126e0dfc860869b0e7ceab1dd06318.zip
Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/urgent
Diffstat (limited to 'fs/xfs/linux-2.6/xfs_sync.c')
-rw-r--r--fs/xfs/linux-2.6/xfs_sync.c30
1 files changed, 27 insertions, 3 deletions
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 6c10f1d2e3d3..594cd822d84d 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -761,8 +761,10 @@ xfs_reclaim_inode(
struct xfs_perag *pag,
int sync_mode)
{
- int error = 0;
+ int error;
+restart:
+ error = 0;
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (!xfs_iflock_nowait(ip)) {
if (!(sync_mode & SYNC_WAIT))
@@ -788,9 +790,31 @@ xfs_reclaim_inode(
if (xfs_inode_clean(ip))
goto reclaim;
- /* Now we have an inode that needs flushing */
- error = xfs_iflush(ip, sync_mode);
+ /*
+ * Now we have an inode that needs flushing.
+ *
+ * We do a nonblocking flush here even if we are doing a SYNC_WAIT
+ * reclaim as we can deadlock with inode cluster removal.
+ * xfs_ifree_cluster() can lock the inode buffer before it locks the
+ * ip->i_lock, and we are doing the exact opposite here. As a result,
+ * doing a blocking xfs_itobp() to get the cluster buffer will result
+ * in an ABBA deadlock with xfs_ifree_cluster().
+ *
+ * As xfs_ifree_cluser() must gather all inodes that are active in the
+ * cache to mark them stale, if we hit this case we don't actually want
+ * to do IO here - we want the inode marked stale so we can simply
+ * reclaim it. Hence if we get an EAGAIN error on a SYNC_WAIT flush,
+ * just unlock the inode, back off and try again. Hopefully the next
+ * pass through will see the stale flag set on the inode.
+ */
+ error = xfs_iflush(ip, SYNC_TRYLOCK | sync_mode);
if (sync_mode & SYNC_WAIT) {
+ if (error == EAGAIN) {
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ /* backoff longer than in xfs_ifree_cluster */
+ delay(2);
+ goto restart;
+ }
xfs_iflock(ip);
goto reclaim;
}