diff options
author | Ben Pfaff <blp@nicira.com> | 2012-08-31 10:11:15 -0700 |
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committer | Ben Pfaff <blp@nicira.com> | 2012-08-31 10:11:15 -0700 |
commit | 45f1a0d993c5fa1ddbf7680f5882e8fc053f1254 (patch) | |
tree | 4a80952a460c0c8190d7863d41697d7052662330 /lib/lockfile.c | |
parent | db90f94066dc645d8e777a9c43ad3f7e745393f9 (diff) | |
download | openvswitch-45f1a0d993c5fa1ddbf7680f5882e8fc053f1254.tar.gz |
lockfile: Log more helpful message when locking fails due to a conflict.
Reported-by: rahim entezari <rahim.entezari@gmail.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
Diffstat (limited to 'lib/lockfile.c')
-rw-r--r-- | lib/lockfile.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/lib/lockfile.c b/lib/lockfile.c index db84aebb4..3708aec0d 100644 --- a/lib/lockfile.c +++ b/lib/lockfile.c @@ -55,7 +55,8 @@ struct lockfile { static struct hmap lock_table = HMAP_INITIALIZER(&lock_table); static void lockfile_unhash(struct lockfile *); -static int lockfile_try_lock(const char *name, struct lockfile **lockfilep); +static int lockfile_try_lock(const char *name, pid_t *pidp, + struct lockfile **lockfilep); /* Returns the name of the lockfile that would be created for locking a file * named 'filename_'. The caller is responsible for freeing the returned name, @@ -98,21 +99,27 @@ lockfile_lock(const char *file, struct lockfile **lockfilep) * stylized ways such that any number of readers may access a file while it * is being written. */ char *lock_name; + pid_t pid; int error; COVERAGE_INC(lockfile_lock); lock_name = lockfile_name(file); - error = lockfile_try_lock(lock_name, lockfilep); + error = lockfile_try_lock(lock_name, &pid, lockfilep); if (error) { COVERAGE_INC(lockfile_error); if (error == EACCES) { error = EAGAIN; } - VLOG_WARN("%s: failed to lock file: %s", - lock_name, strerror(error)); + if (pid) { + VLOG_WARN("%s: cannot lock file because it is already locked by " + "pid %ld", lock_name, (long int) pid); + } else { + VLOG_WARN("%s: failed to lock file: %s", + lock_name, strerror(error)); + } } free(lock_name); @@ -201,7 +208,7 @@ lockfile_register(const char *name, dev_t device, ino_t inode, int fd) } static int -lockfile_try_lock(const char *name, struct lockfile **lockfilep) +lockfile_try_lock(const char *name, pid_t *pidp, struct lockfile **lockfilep) { struct flock l; struct stat s; @@ -209,6 +216,7 @@ lockfile_try_lock(const char *name, struct lockfile **lockfilep) int fd; *lockfilep = NULL; + *pidp = 0; /* Check whether we've already got a lock on that file. */ if (!stat(name, &s)) { @@ -250,6 +258,9 @@ lockfile_try_lock(const char *name, struct lockfile **lockfilep) if (!error) { *lockfilep = lockfile_register(name, s.st_dev, s.st_ino, fd); } else { + if (!fcntl(fd, F_GETLK, &l) && l.l_type != F_UNLCK) { + *pidp = l.l_pid; + } close(fd); } return error; |