From: Steve French stfrench@microsoft.com
commit 71e6864eacbef0b2645ca043cdfbac272cb6cea3 upstream.
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 belegdol@gmail.com Tested-by: Julian Sikorski belegdol@gmail.com Suggested-by: Jeremy Allison jra@samba.org Reviewed-by: Paulo Alcantara (SUSE) pc@cjr.nz Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/cifs/file.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-)
--- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2689,12 +2689,23 @@ int cifs_strict_fsync(struct file *file, 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; } @@ -2706,6 +2717,7 @@ int cifs_fsync(struct file *file, loff_t 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); @@ -2722,12 +2734,23 @@ int cifs_fsync(struct file *file, loff_t 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; }