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author | David Howells <dhowells@redhat.com> | 2024-02-22 14:20:26 +0300 |
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committer | Sasha Levin <sashal@kernel.org> | 2024-03-27 01:17:20 +0300 |
commit | 844b4e132f57f1333dc79feaa035075a096762e4 (patch) | |
tree | d7f58f6a3bcc017c890d5c7d29d5836ad0bc1b55 /fs/smb/client/cifsacl.c | |
parent | e130ce1a71677bd45fe9e4f82dffa2a0c6c772d2 (diff) | |
download | linux-844b4e132f57f1333dc79feaa035075a096762e4.tar.xz |
cifs: Fix writeback data corruption
[ Upstream commit f3dc1bdb6b0b0693562c7c54a6c28bafa608ba3c ]
cifs writeback doesn't correctly handle the case where
cifs_extend_writeback() hits a point where it is considering an additional
folio, but this would overrun the wsize - at which point it drops out of
the xarray scanning loop and calls xas_pause(). The problem is that
xas_pause() advances the loop counter - thereby skipping that page.
What needs to happen is for xas_reset() to be called any time we decide we
don't want to process the page we're looking at, but rather send the
request we are building and start a new one.
Fix this by copying and adapting the netfslib writepages code as a
temporary measure, with cifs writeback intending to be offloaded to
netfslib in the near future.
This also fixes the issue with the use of filemap_get_folios_tag() causing
retry of a bunch of pages which the extender already dealt with.
This can be tested by creating, say, a 64K file somewhere not on cifs
(otherwise copy-offload may get underfoot), mounting a cifs share with a
wsize of 64000, copying the file to it and then comparing the original file
and the copy:
dd if=/dev/urandom of=/tmp/64K bs=64k count=1
mount //192.168.6.1/test /mnt -o user=...,pass=...,wsize=64000
cp /tmp/64K /mnt/64K
cmp /tmp/64K /mnt/64K
Without the fix, the cmp fails at position 64000 (or shortly thereafter).
Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
cc: Shyam Prasad N <sprasad@microsoft.com>
cc: Tom Talpey <tom@talpey.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: samba-technical@lists.samba.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs/smb/client/cifsacl.c')
0 files changed, 0 insertions, 0 deletions