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author | Andrey Vagin <avagin@openvz.org> | 2015-04-16 12:49:38 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-17 09:04:12 -0400 |
commit | 6c8c90319c0bb1c9e0b68e721359b89ae4f28465 (patch) | |
tree | c144b3bde190f4411d36792fc456571df29c678f /fs/proc | |
parent | 15eb42d674de8da66950f78b5c7202accabe026e (diff) | |
download | linux-stable-6c8c90319c0bb1c9e0b68e721359b89ae4f28465.tar.gz linux-stable-6c8c90319c0bb1c9e0b68e721359b89ae4f28465.tar.bz2 linux-stable-6c8c90319c0bb1c9e0b68e721359b89ae4f28465.zip |
proc: show locks in /proc/pid/fdinfo/X
Let's show locks which are associated with a file descriptor in
its fdinfo file.
Currently we don't have a reliable way to determine who holds a lock. We
can find some information in /proc/locks, but PID which is reported there
can be wrong. For example, a process takes a lock, then forks a child and
dies. In this case /proc/locks contains the parent pid, which can be
reused by another process.
$ cat /proc/locks
...
6: FLOCK ADVISORY WRITE 324 00:13:13431 0 EOF
...
$ ps -C rpcbind
PID TTY TIME CMD
332 ? 00:00:00 rpcbind
$ cat /proc/332/fdinfo/4
pos: 0
flags: 0100000
mnt_id: 22
lock: 1: FLOCK ADVISORY WRITE 324 00:13:13431 0 EOF
$ ls -l /proc/332/fd/4
lr-x------ 1 root root 64 Mar 5 14:43 /proc/332/fd/4 -> /run/rpcbind.lock
$ ls -l /proc/324/fd/
total 0
lrwx------ 1 root root 64 Feb 27 14:50 0 -> /dev/pts/0
lrwx------ 1 root root 64 Feb 27 14:50 1 -> /dev/pts/0
lrwx------ 1 root root 64 Feb 27 14:49 2 -> /dev/pts/0
You can see that the process with the 324 pid doesn't hold the lock.
This information is required for proper dumping and restoring file
locks.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: Jeff Layton <jlayton@poochiereds.net>
Acked-by: "J. Bruce Fields" <bfields@fieldses.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/fd.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 8e5ad83b629a..af84ad04df77 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -8,6 +8,7 @@ #include <linux/security.h> #include <linux/file.h> #include <linux/seq_file.h> +#include <linux/fs.h> #include <linux/proc_fs.h> @@ -48,17 +49,23 @@ static int seq_show(struct seq_file *m, void *v) put_files_struct(files); } - if (!ret) { - seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n", - (long long)file->f_pos, f_flags, - real_mount(file->f_path.mnt)->mnt_id); - if (file->f_op->show_fdinfo) - file->f_op->show_fdinfo(m, file); - ret = seq_has_overflowed(m); - fput(file); - } + if (ret) + return ret; - return ret; + seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n", + (long long)file->f_pos, f_flags, + real_mount(file->f_path.mnt)->mnt_id); + + show_fd_locks(m, file, files); + if (seq_has_overflowed(m)) + goto out; + + if (file->f_op->show_fdinfo) + file->f_op->show_fdinfo(m, file); + +out: + fput(file); + return 0; } static int seq_fdinfo_open(struct inode *inode, struct file *file) |