David Howells 91d1dfae46 cifs: Fix FALLOC_FL_ZERO_RANGE to preflush buffered part of target region ... Under certain conditions, the range to be cleared by FALLOC_FL_ZERO_RANGE may only be buffered locally and not yet have been flushed to the server. For example: xfs_io -f -t -c "pwrite -S 0x41 0 4k" \ -c "pwrite -S 0x42 4k 4k" \ -c "fzero 0 4k" \ -c "pread -v 0 8k" /xfstest.test/foo will write two 4KiB blocks of data, which get buffered in the pagecache, and then fallocate() is used to clear the first 4KiB block on the server - but we don't flush the data first, which means the EOF position on the server is wrong, and so the FSCTL_SET_ZERO_DATA RPC fails (and xfs_io ignores the error), but then when we try to read it, we see the old data. Fix this by preflushing any part of the target region that above the server's idea of the EOF position to force the server to update its EOF position. Note, however, that we don't want to simply expand the file by moving the EOF before doing the FSCTL_SET_ZERO_DATA[*] because someone else might see the zeroed region or if the RPC fails we then have to try to clean it up or risk getting corruption. [*] And we have to move the EOF first otherwise FSCTL_SET_ZERO_DATA won't do what we want. This fixes the generic/008 xfstest. [!] Note: A better way to do this might be to split the operation into two parts: we only do FSCTL_SET_ZERO_DATA for the part of the range below the server's EOF and then, if that worked, invalidate the buffered pages for the part above the range. Fixes: 6b69040247 ("cifs/smb3: Fix data inconsistent when zero file range") Signed-off-by: David Howells <dhowells@redhat.com> cc: Steve French <stfrench@microsoft.com> cc: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> cc: Pavel Shilovsky <pshilov@microsoft.com> cc: Paulo Alcantara <pc@manguebit.com> cc: Shyam Prasad N <nspmangalore@gmail.com> cc: Rohith Surabattula <rohiths.msft@gmail.com> cc: Jeff Layton <jlayton@kernel.org> cc: linux-cifs@vger.kernel.org cc: linux-mm@kvack.org Signed-off-by: Steve French <stfrench@microsoft.com>		2024-08-28 16:52:17 -05:00
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client	cifs: Fix FALLOC_FL_ZERO_RANGE to preflush buffered part of target region	2024-08-28 16:52:17 -05:00
common	smb: smb2pdu.h: Use static_assert() to check struct sizes	2024-08-15 16:06:55 -05:00
server	smb/server: update misguided comment of smb2_allocate_rsp_buf()	2024-08-22 09:52:00 -05:00
Kconfig	smb: move client and server files to common directory fs/smb	2023-05-24 16:29:21 -05:00
Makefile	smb: move client and server files to common directory fs/smb	2023-05-24 16:29:21 -05:00