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authorAndrey Vagin <avagin@openvz.org>2015-04-16 12:49:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-17 09:04:12 -0400
commit6c8c90319c0bb1c9e0b68e721359b89ae4f28465 (patch)
treec144b3bde190f4411d36792fc456571df29c678f
parent15eb42d674de8da66950f78b5c7202accabe026e (diff)
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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>
-rw-r--r--Documentation/filesystems/proc.txt4
-rw-r--r--fs/locks.c38
-rw-r--r--fs/proc/fd.c27
-rw-r--r--include/linux/fs.h7
4 files changed, 66 insertions, 10 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 6d370622fdfe..8e36c7e3c345 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1709,6 +1709,10 @@ A typical output is
flags: 0100002
mnt_id: 19
+All locks associated with a file descriptor are shown in its fdinfo too.
+
+lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
+
The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
pair provide additional information particular to the objects they represent.
diff --git a/fs/locks.c b/fs/locks.c
index 52b780fb5258..653faabb07f4 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2590,6 +2590,44 @@ static int locks_show(struct seq_file *f, void *v)
return 0;
}
+static void __show_fd_locks(struct seq_file *f,
+ struct list_head *head, int *id,
+ struct file *filp, struct files_struct *files)
+{
+ struct file_lock *fl;
+
+ list_for_each_entry(fl, head, fl_list) {
+
+ if (filp != fl->fl_file)
+ continue;
+ if (fl->fl_owner != files &&
+ fl->fl_owner != filp)
+ continue;
+
+ (*id)++;
+ seq_puts(f, "lock:\t");
+ lock_get_status(f, fl, *id, "");
+ }
+}
+
+void show_fd_locks(struct seq_file *f,
+ struct file *filp, struct files_struct *files)
+{
+ struct inode *inode = file_inode(filp);
+ struct file_lock_context *ctx;
+ int id = 0;
+
+ ctx = inode->i_flctx;
+ if (!ctx)
+ return;
+
+ spin_lock(&ctx->flc_lock);
+ __show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
+ __show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
+ __show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
+ spin_unlock(&ctx->flc_lock);
+}
+
static void *locks_start(struct seq_file *f, loff_t *pos)
__acquires(&blocked_lock_lock)
{
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)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6bf7ab7c1573..c4e927358503 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1042,6 +1042,9 @@ extern void lease_get_mtime(struct inode *, struct timespec *time);
extern int generic_setlease(struct file *, long, struct file_lock **, void **priv);
extern int vfs_setlease(struct file *, long, struct file_lock **, void **);
extern int lease_modify(struct file_lock *, int, struct list_head *);
+struct files_struct;
+extern void show_fd_locks(struct seq_file *f,
+ struct file *filp, struct files_struct *files);
#else /* !CONFIG_FILE_LOCKING */
static inline int fcntl_getlk(struct file *file, unsigned int cmd,
struct flock __user *user)
@@ -1178,6 +1181,10 @@ static inline int lease_modify(struct file_lock *fl, int arg,
{
return -EINVAL;
}
+
+struct files_struct;
+static inline void show_fd_locks(struct seq_file *f,
+ struct file *filp, struct files_struct *files) {}
#endif /* !CONFIG_FILE_LOCKING */