From 90f7d7a0d0d68623b5f7df5621a8d54d9518fcc4 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 10 Sep 2021 15:36:29 -0400 Subject: [PATCH] locks: remove LOCK_MAND flock lock support As best I can tell, the logic for these has been broken for a long time (at least before the move to git), such that they never conflict with anything. Also, nothing checks for these flags and prevented opens or read/write behavior on the files. They don't seem to do anything. Given that, we can rip these symbols out of the kernel, and just make flock(2) return 0 when LOCK_MAND is set in order to preserve existing behavior. Cc: Matthew Wilcox Cc: Stephen Rothwell Signed-off-by: Jeff Layton --- fs/ceph/locks.c | 3 -- fs/gfs2/file.c | 2 -- fs/locks.c | 47 +++++++++++++++----------------- fs/nfs/file.c | 9 ------ include/uapi/asm-generic/fcntl.h | 4 +++ 5 files changed, 26 insertions(+), 39 deletions(-) diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c index bdeb271f47d9..d8c31069fbf2 100644 --- a/fs/ceph/locks.c +++ b/fs/ceph/locks.c @@ -302,9 +302,6 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl) if (!(fl->fl_flags & FL_FLOCK)) return -ENOLCK; - /* No mandatory locks */ - if (fl->fl_type & LOCK_MAND) - return -EOPNOTSUPP; dout("ceph_flock, fl_file: %p\n", fl->fl_file); diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c index c559827cb6f9..078ef29e31bc 100644 --- a/fs/gfs2/file.c +++ b/fs/gfs2/file.c @@ -1338,8 +1338,6 @@ static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl) { if (!(fl->fl_flags & FL_FLOCK)) return -ENOLCK; - if (fl->fl_type & LOCK_MAND) - return -EOPNOTSUPP; if (fl->fl_type == F_UNLCK) { do_unflock(file, fl); diff --git a/fs/locks.c b/fs/locks.c index 3d6fb4ae847b..d397394633be 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -461,8 +461,6 @@ static void locks_move_blocks(struct file_lock *new, struct file_lock *fl) } static inline int flock_translate_cmd(int cmd) { - if (cmd & LOCK_MAND) - return cmd & (LOCK_MAND | LOCK_RW); switch (cmd) { case LOCK_SH: return F_RDLCK; @@ -942,8 +940,6 @@ static bool flock_locks_conflict(struct file_lock *caller_fl, */ if (caller_fl->fl_file == sys_fl->fl_file) return false; - if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) - return false; return locks_conflict(caller_fl, sys_fl); } @@ -2116,11 +2112,9 @@ EXPORT_SYMBOL(locks_lock_inode_wait); * - %LOCK_SH -- a shared lock. * - %LOCK_EX -- an exclusive lock. * - %LOCK_UN -- remove an existing lock. - * - %LOCK_MAND -- a 'mandatory' flock. - * This exists to emulate Windows Share Modes. + * - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED) * - * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other - * processes read and write access respectively. + * %LOCK_MAND support has been removed from the kernel. */ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) { @@ -2137,9 +2131,22 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) cmd &= ~LOCK_NB; unlock = (cmd == LOCK_UN); - if (!unlock && !(cmd & LOCK_MAND) && - !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) + if (!unlock && !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) + goto out_putf; + + /* + * LOCK_MAND locks were broken for a long time in that they never + * conflicted with one another and didn't prevent any sort of open, + * read or write activity. + * + * Just ignore these requests now, to preserve legacy behavior, but + * throw a warning to let people know that they don't actually work. + */ + if (cmd & LOCK_MAND) { + pr_warn_once("Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n"); + error = 0; goto out_putf; + } lock = flock_make_lock(f.file, cmd, NULL); if (IS_ERR(lock)) { @@ -2718,6 +2725,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, struct inode *inode = NULL; unsigned int fl_pid; struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); + int type; fl_pid = locks_translate_pid(fl, proc_pidns); /* @@ -2745,11 +2753,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, seq_printf(f, " %s ", (inode == NULL) ? "*NOINODE*" : "ADVISORY "); } else if (IS_FLOCK(fl)) { - if (fl->fl_type & LOCK_MAND) { - seq_puts(f, "FLOCK MSNFS "); - } else { - seq_puts(f, "FLOCK ADVISORY "); - } + seq_puts(f, "FLOCK ADVISORY "); } else if (IS_LEASE(fl)) { if (fl->fl_flags & FL_DELEG) seq_puts(f, "DELEG "); @@ -2765,17 +2769,10 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, } else { seq_puts(f, "UNKNOWN UNKNOWN "); } - if (fl->fl_type & LOCK_MAND) { - seq_printf(f, "%s ", - (fl->fl_type & LOCK_READ) - ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " - : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); - } else { - int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type; + type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type; - seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" : - (type == F_RDLCK) ? "READ" : "UNLCK"); - } + seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" : + (type == F_RDLCK) ? "READ" : "UNLCK"); if (inode) { /* userspace relies on this representation of dev_t */ seq_printf(f, "%d %02x:%02x:%lu ", fl_pid, diff --git a/fs/nfs/file.c b/fs/nfs/file.c index aa353fd58240..24e7dccce355 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -843,15 +843,6 @@ int nfs_flock(struct file *filp, int cmd, struct file_lock *fl) if (!(fl->fl_flags & FL_FLOCK)) return -ENOLCK; - /* - * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of - * any standard. In principle we might be able to support LOCK_MAND - * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the - * NFS code is not set up for it. - */ - if (fl->fl_type & LOCK_MAND) - return -EINVAL; - if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK) is_local = 1; diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h index 9dc0bf0c5a6e..ecd0f5bdfc1d 100644 --- a/include/uapi/asm-generic/fcntl.h +++ b/include/uapi/asm-generic/fcntl.h @@ -181,6 +181,10 @@ struct f_owner_ex { blocking */ #define LOCK_UN 8 /* remove lock */ +/* + * LOCK_MAND support has been removed from the kernel. We leave the symbols + * here to not break legacy builds, but these should not be used in new code. + */ #define LOCK_MAND 32 /* This is a mandatory flock ... */ #define LOCK_READ 64 /* which allows concurrent read operations */ #define LOCK_WRITE 128 /* which allows concurrent write operations */ -- 2.25.1