From 71e6864eacbef0b2645ca043cdfbac272cb6cea3 Mon Sep 17 00:00:00 2001 From: Steve French Date: Wed, 10 Nov 2021 01:47:48 -0600 Subject: smb3: do not error on fsync when readonly Linux allows doing a flush/fsync on a file open for read-only, but the protocol does not allow that. If the file passed in on the flush is read-only try to find a writeable handle for the same inode, if that is not possible skip sending the fsync call to the server to avoid breaking the apps. Reported-by: Julian Sikorski Tested-by: Julian Sikorski Suggested-by: Jeremy Allison Reviewed-by: Paulo Alcantara (SUSE) Signed-off-by: Steve French --- fs/cifs/file.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) (limited to 'fs') diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 1b855fcb179e..9fee3af83a73 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2692,12 +2692,23 @@ int cifs_strict_fsync(struct file *file, loff_t start, loff_t end, tcon = tlink_tcon(smbfile->tlink); if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) { server = tcon->ses->server; - if (server->ops->flush) - rc = server->ops->flush(xid, tcon, &smbfile->fid); - else + if (server->ops->flush == NULL) { rc = -ENOSYS; + goto strict_fsync_exit; + } + + if ((OPEN_FMODE(smbfile->f_flags) & FMODE_WRITE) == 0) { + smbfile = find_writable_file(CIFS_I(inode), FIND_WR_ANY); + if (smbfile) { + rc = server->ops->flush(xid, tcon, &smbfile->fid); + cifsFileInfo_put(smbfile); + } else + cifs_dbg(FYI, "ignore fsync for file not open for write\n"); + } else + rc = server->ops->flush(xid, tcon, &smbfile->fid); } +strict_fsync_exit: free_xid(xid); return rc; } @@ -2709,6 +2720,7 @@ int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync) struct cifs_tcon *tcon; struct TCP_Server_Info *server; struct cifsFileInfo *smbfile = file->private_data; + struct inode *inode = file_inode(file); struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file); rc = file_write_and_wait_range(file, start, end); @@ -2725,12 +2737,23 @@ int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync) tcon = tlink_tcon(smbfile->tlink); if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) { server = tcon->ses->server; - if (server->ops->flush) - rc = server->ops->flush(xid, tcon, &smbfile->fid); - else + if (server->ops->flush == NULL) { rc = -ENOSYS; + goto fsync_exit; + } + + if ((OPEN_FMODE(smbfile->f_flags) & FMODE_WRITE) == 0) { + smbfile = find_writable_file(CIFS_I(inode), FIND_WR_ANY); + if (smbfile) { + rc = server->ops->flush(xid, tcon, &smbfile->fid); + cifsFileInfo_put(smbfile); + } else + cifs_dbg(FYI, "ignore fsync for file not open for write\n"); + } else + rc = server->ops->flush(xid, tcon, &smbfile->fid); } +fsync_exit: free_xid(xid); return rc; } -- cgit v1.2.3