GFS2: filesystem hang caused by incorrect lock order

This patch fixes a deadlock in GFS2 where two processes are trying
to reclaim an unlinked dinode:
One holds the inode glock and calls gfs2_lookup_by_inum trying to look
up the inode, which it can't, due to I_FREEING.  The other has set
I_FREEING from vfs and is at the beginning of gfs2_delete_inode
waiting for the glock, which is held by the first.  The solution is to
add a new non_block parameter to the gfs2_iget function that causes it
to return -ENOENT if the inode is being freed.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index cf930cd9664a..6fcae8469f6d 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -945,7 +945,7 @@ static void try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked, u64 skip
                 /* rgblk_search can return a block < goal, so we need to
                    keep it marching forward. */
                 no_addr = block + rgd->rd_data0;
-                goal++;
+                goal = max(block + 1, goal + 1);
                 if (*last_unlinked != NO_BLOCK && no_addr <= *last_unlinked)
                         continue;
                 if (no_addr == skip)
@@ -971,7 +971,7 @@ static void try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked, u64 skip
                         found++;
 
                 /* Limit reclaim to sensible number of tasks */
-                if (found > 2*NR_CPUS)
+                if (found > NR_CPUS)
                         return;
         }