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[v2,1/2] cifs/smb3: Fix data inconsistent when punch hole

Message ID 20200623113154.2629513-2-zhangxiaoxu5@huawei.com
State New
Headers show
Series cifs: Fix data insonsistent when fallocate | expand

Commit Message

Zhang Xiaoxu June 23, 2020, 11:31 a.m. UTC
When punch hole success, we also can read old data from file:
  # strace -e trace=pread64,fallocate xfs_io -f -c "pread 20 40" \
           -c "fpunch 20 40" -c"pread 20 40" file
  pread64(3, " version 5.8.0-rc1+"..., 40, 20) = 40
  fallocate(3, FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE, 20, 40) = 0
  pread64(3, " version 5.8.0-rc1+"..., 40, 20) = 40

CIFS implements the fallocate(FALLOCATE_FL_PUNCH_HOLE) with send SMB
ioctl(FSCTL_SET_ZERO_DATA) to server. It just set the range of the
remote file to zero, but local page caches not updated, then the
local page caches inconsistent with server.

Also can be found by xfstests generic/316.

So, we need to remove the page caches before send the SMB
ioctl(FSCTL_SET_ZERO_DATA) to server.

Fixes: 31742c5a33176 ("enable fallocate punch hole ("fallocate -p") for SMB3")
Suggested-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Cc: stable@vger.kernel.org # v3.17
---
 fs/cifs/smb2ops.c | 6 ++++++
 1 file changed, 6 insertions(+)
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Patch

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 736d86b8a910..02fe77b2f517 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3253,6 +3253,12 @@  static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
 		return rc;
 	}
 
+	/*
+	 * We implement the punch hole through ioctl, so we need remove the page
+	 * caches first, otherwise the data may be inconsistent with the server.
+	 */
+	truncate_pagecache_range(inode, offset, offset + len - 1);
+
 	cifs_dbg(FYI, "Offset %lld len %lld\n", offset, len);
 
 	fsctl_buf.FileOffset = cpu_to_le64(offset);