6.6-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit 91d1dfae464987aaf6c79ff51d8674880fb3be77 ]
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: 6b69040247e1 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/smb2ops.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index 012d6ec12a69..acd5d7d79352 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -3186,13 +3186,15 @@ static long smb3_zero_data(struct file *file, struct cifs_tcon *tcon, }
static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon, - loff_t offset, loff_t len, bool keep_size) + unsigned long long offset, unsigned long long len, + bool keep_size) { struct cifs_ses *ses = tcon->ses; struct inode *inode = file_inode(file); struct cifsInodeInfo *cifsi = CIFS_I(inode); struct cifsFileInfo *cfile = file->private_data; - unsigned long long new_size; + struct netfs_inode *ictx = netfs_inode(inode); + unsigned long long i_size, new_size, remote_size; long rc; unsigned int xid;
@@ -3204,6 +3206,16 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon, inode_lock(inode); filemap_invalidate_lock(inode->i_mapping);
+ i_size = i_size_read(inode); + remote_size = ictx->remote_i_size; + if (offset + len >= remote_size && offset < i_size) { + unsigned long long top = umin(offset + len, i_size); + + rc = filemap_write_and_wait_range(inode->i_mapping, offset, top - 1); + if (rc < 0) + goto zero_range_exit; + } + /* * We zero the range through ioctl, so we need remove the page caches * first, otherwise the data may be inconsistent with the server.