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[PATCH] xfs: use KM_NOFS for allocations during attribute list operation

To: xfs@xxxxxxxxxxx
Subject: [PATCH] xfs: use KM_NOFS for allocations during attribute list operations
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 21 Dec 2010 11:56:33 +1100
From: Dave Chinner <dchinner@xxxxxxxxxx>

When listing attributes, we are doiing memory allocations under the
inode ilock using only KM_SLEEP. This allows memory allocation to
recurse back into the filesystem and do writeback, which may the
ilock we already hold on the current inode. THis will deadlock.
Hence use KM_NOFS for such allocations outside of transaction
context to ensure that reclaim recursion does not occur.

Reported-by: Nick Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
 fs/xfs/xfs_attr_leaf.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_attr_leaf.c b/fs/xfs/xfs_attr_leaf.c
index a6cff8e..71e90dc2 100644
--- a/fs/xfs/xfs_attr_leaf.c
+++ b/fs/xfs/xfs_attr_leaf.c
@@ -637,7 +637,7 @@ xfs_attr_shortform_list(xfs_attr_list_context_t *context)
         * It didn't all fit, so we have to sort everything on hashval.
        sbsize = sf->hdr.count * sizeof(*sbuf);
-       sbp = sbuf = kmem_alloc(sbsize, KM_SLEEP);
+       sbp = sbuf = kmem_alloc(sbsize, KM_SLEEP | KM_NOFS);
         * Scan the attribute list for the rest of the entries, storing
@@ -2386,7 +2386,7 @@ xfs_attr_leaf_list_int(xfs_dabuf_t *bp, 
xfs_attr_list_context_t *context)
                                args.dp = context->dp;
                                args.whichfork = XFS_ATTR_FORK;
                                args.valuelen = valuelen;
-                               args.value = kmem_alloc(valuelen, KM_SLEEP);
+                               args.value = kmem_alloc(valuelen, KM_SLEEP | 
                                args.rmtblkno = be32_to_cpu(name_rmt->valueblk);
                                args.rmtblkcnt = XFS_B_TO_FSB(args.dp->i_mount, 
                                retval = xfs_attr_rmtval_get(&args);

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