6.10-stable review patch. If anyone has any objections, please let me know.
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From: Steve French stfrench@microsoft.com
commit 836bb3268db405cf9021496ac4dbc26d3e4758fe upstream.
Mandatory locking is enforced for cached writes, which violates default posix semantics, and also it is enforced inconsistently. This apparently breaks recent versions of libreoffice, but can also be demonstrated by opening a file twice from the same client, locking it from handle one and writing to it from handle two (which fails, returning EACCES).
Since there was already a mount option "forcemandatorylock" (which defaults to off), with this change only when the user intentionally specifies "forcemandatorylock" on mount will we break posix semantics on write to a locked range (ie we will only fail the write in this case, if the user mounts with "forcemandatorylock").
Fixes: 85160e03a79e ("CIFS: Implement caching mechanism for mandatory brlocks") Cc: stable@vger.kernel.org Cc: Pavel Shilovsky piastryyy@gmail.com Reported-by: abartlet@samba.org Reported-by: Kevin Ottens kevin.ottens@enioka.com Reviewed-by: David Howells dhowells@redhat.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/file.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -2719,6 +2719,7 @@ cifs_writev(struct kiocb *iocb, struct i struct inode *inode = file->f_mapping->host; struct cifsInodeInfo *cinode = CIFS_I(inode); struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server; + struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb); ssize_t rc;
rc = netfs_start_io_write(inode); @@ -2735,12 +2736,16 @@ cifs_writev(struct kiocb *iocb, struct i if (rc <= 0) goto out;
- if (!cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from), + if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) && + (cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from), server->vals->exclusive_lock_type, 0, - NULL, CIFS_WRITE_OP)) - rc = netfs_buffered_write_iter_locked(iocb, from, NULL); - else + NULL, CIFS_WRITE_OP))) { rc = -EACCES; + goto out; + } + + rc = netfs_buffered_write_iter_locked(iocb, from, NULL); + out: up_read(&cinode->lock_sem); netfs_end_io_write(inode);