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[PATCH 04/10] xfs: fallback to vmalloc for large buffers in xfs_getbmap

To: xfs@xxxxxxxxxxx
Subject: [PATCH 04/10] xfs: fallback to vmalloc for large buffers in xfs_getbmap
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 7 Mar 2012 15:50:22 +1100
In-reply-to: <1331095828-28742-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1331095828-28742-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

xfs_getbmap uses for a large buffer for extents, which is kmalloc'd.
This can fail after the system has been running for some time as it
is a high order allocation. Add a fallback to vmalloc so that it
doesn't require contiguous memory and so won't randomly fail on
files with large extent lists.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/xfs_bmap.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 188ef2f..3548c6f 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -5536,8 +5536,12 @@ xfs_getbmap(
        if (bmv->bmv_count > ULONG_MAX / sizeof(struct getbmapx))
                return XFS_ERROR(ENOMEM);
        out = kmem_zalloc(bmv->bmv_count * sizeof(struct getbmapx), KM_MAYFAIL);
-       if (!out)
-               return XFS_ERROR(ENOMEM);
+       if (!out) {
+               out = kmem_zalloc_large(bmv->bmv_count *
+                                       sizeof(struct getbmapx));
+               if (!out)
+                       return XFS_ERROR(ENOMEM);
+       }
 
        xfs_ilock(ip, XFS_IOLOCK_SHARED);
        if (whichfork == XFS_DATA_FORK && !(iflags & BMV_IF_DELALLOC)) {
@@ -5661,7 +5665,10 @@ xfs_getbmap(
                        break;
        }
 
-       kmem_free(out);
+       if (is_vmalloc_addr(out))
+               kmem_free_large(out);
+       else
+               kmem_free(out);
        return error;
 }
 
-- 
1.7.9

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