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[PATCH] xfs: don't perform discard if the given range length is less th

To: "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
Subject: [PATCH] xfs: don't perform discard if the given range length is less than block size
From: Jeff Liu <jeff.liu@xxxxxxxxxx>
Date: Wed, 20 Nov 2013 16:08:53 +0800
Delivered-to: xfs@xxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0
From: Jie Liu <jeff.liu@xxxxxxxxxx>

For discard operation, we should return EINVAL if the given range length
is less than a block size, otherwise it will go through the file system
to discard data blocks as the end range might be evaluated to -1, e.g,
# fstrim -v -o 0 -l 100 /xfs7
/xfs7: 9811378176 bytes were trimmed

This issue can be triggered via xfstests/generic/288.

Also, it seems to get the request queue pointer via bdev_get_queue()
instead of the hard code pointer dereference is not a bad thing.

Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
 fs/xfs/xfs_discard.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
index 8367d6d..4f11ef0 100644
--- a/fs/xfs/xfs_discard.c
+++ b/fs/xfs/xfs_discard.c
@@ -157,7 +157,7 @@ xfs_ioc_trim(
        struct xfs_mount                *mp,
        struct fstrim_range __user      *urange)
-       struct request_queue    *q = mp->m_ddev_targp->bt_bdev->bd_disk->queue;
+       struct request_queue    *q = bdev_get_queue(mp->m_ddev_targp->bt_bdev);
        unsigned int            granularity = q->limits.discard_granularity;
        struct fstrim_range     range;
        xfs_daddr_t             start, end, minlen;
@@ -180,7 +180,8 @@ xfs_ioc_trim(
         * matter as trimming blocks is an advisory interface.
        if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks) ||
-           range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)))
+           range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)) ||
+           range.len < mp->m_sb.sb_blocksize)
                return -XFS_ERROR(EINVAL);
        start = BTOBB(range.start);

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