7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paulo Alcantara commit 8f8d32c1044f70e46e87550e039a15ff20a4b21c upstream. smb3_zero_range() emulates FALLOC_FL_ZERO_RANGE by invalidating the page cache over the target range with truncate_pagecache_range() and then issuing FSCTL_SET_ZERO_DATA to the server. Dirty data was only flushed conditionally, when the range reached or extended EOF. For a purely interior zero range that does not reach EOF, no flush happened, so a dirty folio overlapping the range could be written back to the server after the FSCTL and refill the range that was just zeroed with stale data. Fix this by unconditionally flushing and waiting for dirty data in the range before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA, exactly as was done for smb3_punch_hole() in commit d7d2adcd022b ("smb/client: flush dirty data before punching a hole"); the two paths are structurally identical here. This is observed as generic/363 randomly reading stale data where a zeroed range is expected against Windows Server. Fixes: 91d1dfae4649 ("cifs: Fix FALLOC_FL_ZERO_RANGE to preflush buffered part of target region") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/smb2ops.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -3559,13 +3559,11 @@ static long smb3_zero_range(struct file filemap_invalidate_lock(inode->i_mapping); netfs_read_sizes(inode, &i_size, &remote_i_size, &zero_point); - if (offset + len >= remote_i_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; - } + rc = filemap_write_and_wait_range(inode->i_mapping, offset, + offset + len - 1); + if (rc < 0) + goto zero_range_exit; /* * We zero the range through ioctl, so we need remove the page caches