libmount: use libmnt_lock for utab flock

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/shlibs/mount/src/context.c b/shlibs/mount/src/context.c
index eedb8234553f3e4b17bb0523bf55f952d2fb5d32..1968a4b34c32d8ac33e625db74e9f8c1eaa4a972 100644 (file)
--- a/shlibs/mount/src/context.c
+++ b/shlibs/mount/src/context.c
@@ -798,8 +798,9 @@ struct libmnt_cache *mnt_context_get_cache(struct libmnt_context *cxt)
  * small exception: the application has to be able to remove the lock file when
  * interrupted by signal or signals have to be ignored when the lock is locked.
  *
- * The default behavior is to ignore all signals (except SIGALRM and SIGTRAP)
- * when the lock is locked. If this behavior is unacceptable then use:
+ * The default behavior is to ignore all signals (except SIGALRM and
+ * SIGTRAP for mtab udate) when the lock is locked. If this behavior
+ * is unacceptable then use:
  *
  *     lc = mnt_context_get_lock(cxt);
  *     if (lc)
@@ -807,18 +808,21 @@ struct libmnt_cache *mnt_context_get_cache(struct libmnt_context *cxt)
  *
  * and don't forget to call mnt_unlock_file(lc) before exit.
  *
- * This function returns NULL if the lock is unnecessary (mtab file is not writable
- * or /etc/mtab is symlink to /proc/mounts).
- *
  * Returns: pointer to lock struct or NULL.
  */
 struct libmnt_lock *mnt_context_get_lock(struct libmnt_context *cxt)
 {
-       if (!cxt || (cxt->flags & MNT_FL_NOMTAB) || !cxt->mtab_writable)
+       /*
+        * DON'T call this function within libmount, it will always allocate
+        * the lock. The mnt_update_* functions are able to allocate the lock
+        * only when mtab/utab update is really necessary.
+        */
+       if (!cxt || (cxt->flags & MNT_FL_NOMTAB))
                return NULL;
 
-       if (!cxt->lock && cxt->mtab_path) {
-               cxt->lock = mnt_new_lock(cxt->mtab_path, 0);
+       if (!cxt->lock) {
+               cxt->lock = mnt_new_lock(cxt->mtab_writable ?
+                               cxt->mtab_path : cxt->utab_path, 0);
                if (cxt->lock)
                        mnt_lock_block_signals(cxt->lock, TRUE);
        }
@@ -1323,7 +1327,7 @@ int mnt_context_update_tabs(struct libmnt_context *cxt)
                mnt_update_force_rdonly(cxt->update,
                                cxt->mountflags & MS_RDONLY);
 
-       return mnt_update_table(cxt->update, mnt_context_get_lock(cxt));
+       return mnt_update_table(cxt->update, cxt->lock);
 }
 
 static int apply_table(struct libmnt_context *cxt, struct libmnt_table *tb,
@@ -1610,6 +1614,9 @@ int test_mount(struct libmnt_test *ts, int argc, char *argv[])
                mnt_context_set_target(cxt, argv[idx++]);
        }
 
+       /* this is unnecessary -- libmount is able to internaly
+        * create and manage the lock
+        */
        lock = mnt_context_get_lock(cxt);
        if (lock)
                atexit(lock_fallback);

diff --git a/shlibs/mount/src/lock.c b/shlibs/mount/src/lock.c
index daf204496137d5e6336c2013cbfa4919c91d5cd3..53c1115ece687d82ac8840de8fd3c487d3650e84 100644 (file)
--- a/shlibs/mount/src/lock.c
+++ b/shlibs/mount/src/lock.c
@@ -88,7 +88,7 @@ struct libmnt_lock *mnt_new_lock(const char *datafile, pid_t id)
        ml->linkfile = ln;
        ml->lockfile = lo;
 
-       DBG(LOCKS, mnt_debug_h(ml, "alloc: linkfile=%s, lockfile=%s", ln, lo));
+       DBG(LOCKS, mnt_debug_h(ml, "alloc: default linkfile=%s, lockfile=%s", ln, lo));
        return ml;
 err:
        free(lo);
@@ -160,7 +160,7 @@ int mnt_lock_use_simplelock(struct libmnt_lock *ml, int enable)
        else if (!ml->simplelock && endswith(ml->lockfile, ".lock"))
                 memcpy(ml->lockfile + sz - 5, "~", 2);
 
-       DBG(LOCKS, mnt_debug_h(ml, "lock filename: '%s'", ml->lockfile));
+       DBG(LOCKS, mnt_debug_h(ml, "new lock filename: '%s'", ml->lockfile));
        return 0;
 }
 
@@ -234,6 +234,7 @@ static int lock_simplelock(struct libmnt_lock *ml)
                rc = -errsv;
                goto err;
        }
+       ml->locked = 1;
        return 0;
 err:
        if (ml->sigblock)

diff --git a/shlibs/mount/src/tab_update.c b/shlibs/mount/src/tab_update.c
index 4822dffc5e8589aa3704a31d18d353707ed3ef90..d51464184535087b28deacd9743ac819a1f92dea 100644 (file)
--- a/shlibs/mount/src/tab_update.c
+++ b/shlibs/mount/src/tab_update.c
@@ -41,9 +41,6 @@ struct libmnt_update {
        unsigned long   mountflags;
        int             userspace_only;
        int             ready;
-
-       sigset_t        oldsigmask;
-       int             utab_lock;
 };
 
 static int utab_new_entry(struct libmnt_fs *fs, unsigned long mountflags, struct libmnt_fs **ent);
@@ -62,7 +59,6 @@ struct libmnt_update *mnt_new_update(void)
        if (!upd)
                return NULL;
 
-       upd->utab_lock = -1;
        DBG(UPDATE, mnt_debug_h(upd, "allocate"));
        return upd;
 }
@@ -132,14 +128,13 @@ int mnt_update_set_filename(struct libmnt_update *upd, const char *filename,
  * mnt_update_get_filename:
  * @upd: update
  *
- * This function returns file name (e.g. /etc/mtab) if the update
- * should be covered by mnt_lock, otherwise returne NULL.
+ * This function returns file name (e.g. /etc/mtab) for the up-dated file.
  *
  * Returns: pointer to filename that will be updated or NULL in case of error.
  */
 const char *mnt_update_get_filename(struct libmnt_update *upd)
 {
-       return upd && !upd->userspace_only ? upd->filename : NULL;
+       return upd ? upd->filename : NULL;
 }
 
 /**
@@ -634,63 +629,6 @@ leave:
        return rc;
 }
 
-static int utab_lock(struct libmnt_update *upd)
-{
-       char *lfile;
-       int rc;
-       sigset_t sigs;
-
-       assert(upd);
-       assert(upd->filename);
-       assert(upd->userspace_only);
-
-       if (asprintf(&lfile, "%s.lock", upd->filename) == -1)
-               return -1;
-
-       DBG(UPDATE, mnt_debug("%s: locking", lfile));
-
-       sigemptyset(&upd->oldsigmask);
-       sigfillset(&sigs);
-       sigprocmask(SIG_BLOCK, &sigs, &upd->oldsigmask);
-
-       upd->utab_lock = open(lfile, O_RDONLY|O_CREAT|O_CLOEXEC, S_IWUSR|
-                                    S_IRUSR|S_IRGRP|S_IROTH);
-       free(lfile);
-
-       if (upd->utab_lock < 0) {
-               rc = -errno;
-               goto err;
-       }
-
-       while (flock(upd->utab_lock, LOCK_EX) < 0) {
-               int errsv;
-               if ((errno == EAGAIN) || (errno == EINTR))
-                       continue;
-               errsv = errno;
-               close(upd->utab_lock);
-               upd->utab_lock = -1;
-               rc = -errsv;
-               goto err;
-       }
-       return 0;
-err:
-       sigprocmask(SIG_SETMASK, &upd->oldsigmask, NULL);
-       return rc;
-}
-
-static void utab_unlock(struct libmnt_update *upd)
-{
-       assert(upd);
-       assert(upd->userspace_only);
-
-       if (upd->utab_lock >= 0) {
-               DBG(UPDATE, mnt_debug("unlocking utab"));
-               close(upd->utab_lock);
-               upd->utab_lock = -1;
-               sigprocmask(SIG_SETMASK, &upd->oldsigmask, NULL);
-       }
-}
-
 static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
 {
        struct libmnt_table *tb;
@@ -701,9 +639,7 @@ static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
 
        DBG(UPDATE, mnt_debug_h(upd, "%s: add entry", upd->filename));
 
-       if (upd->userspace_only)
-               rc = utab_lock(upd);
-       else if (lc)
+       if (lc)
                rc = mnt_lock_file(lc);
        if (rc)
                return rc;
@@ -720,9 +656,7 @@ static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
                }
        }
 
-       if (upd->userspace_only)
-               utab_unlock(upd);
-       else if (lc)
+       if (lc)
                mnt_unlock_file(lc);
 
        mnt_free_table(tb);
@@ -739,9 +673,7 @@ static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc
 
        DBG(UPDATE, mnt_debug_h(upd, "%s: remove entry", upd->filename));
 
-       if (upd->userspace_only)
-               rc = utab_lock(upd);
-       else if (lc)
+       if (lc)
                rc = mnt_lock_file(lc);
        if (rc)
                return rc;
@@ -757,9 +689,7 @@ static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc
                }
        }
 
-       if (upd->userspace_only)
-               utab_unlock(upd);
-       else if (lc)
+       if (lc)
                mnt_unlock_file(lc);
 
        mnt_free_table(tb);
@@ -773,9 +703,7 @@ static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *l
 
        DBG(UPDATE, mnt_debug_h(upd, "%s: modify target", upd->filename));
 
-       if (upd->userspace_only)
-               rc = utab_lock(upd);
-       else if (lc)
+       if (lc)
                rc = mnt_lock_file(lc);
        if (rc)
                return rc;
@@ -792,9 +720,7 @@ static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *l
                }
        }
 
-       if (upd->userspace_only)
-               utab_unlock(upd);
-       else if (lc)
+       if (lc)
                mnt_unlock_file(lc);
 
        mnt_free_table(tb);
@@ -814,9 +740,7 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
 
        fs = upd->fs;
 
-       if (upd->userspace_only)
-               rc = utab_lock(upd);
-       else if (lc)
+       if (lc)
                rc = mnt_lock_file(lc);
        if (rc)
                return rc;
@@ -837,9 +761,7 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
                }
        }
 
-       if (upd->userspace_only)
-               utab_unlock(upd);
-       else if (lc)
+       if (lc)
                mnt_unlock_file(lc);
 
        mnt_free_table(tb);
@@ -876,11 +798,13 @@ int mnt_update_table(struct libmnt_update *upd, struct libmnt_lock *lc)
        if (upd->fs) {
                DBG(UPDATE, mnt_fs_print_debug(upd->fs, stderr));
        }
-       if (!lc && !upd->userspace_only) {
+       if (!lc) {
                lc = mnt_new_lock(upd->filename, 0);
                if (lc)
                        mnt_lock_block_signals(lc, TRUE);
        }
+       if (lc && upd->userspace_only)
+               mnt_lock_use_simplelock(lc, TRUE);      /* use flock */
 
        if (!upd->fs && upd->target)
                rc = update_remove_entry(upd, lc);      /* umount */
@@ -894,10 +818,8 @@ int mnt_update_table(struct libmnt_update *upd, struct libmnt_lock *lc)
        upd->ready = FALSE;
        DBG(UPDATE, mnt_debug_h(upd, "%s: update tab: done [rc=%d]",
                                upd->filename, rc));
-
        if (lc != lc0)
                 mnt_free_lock(lc);
-
        return rc;
 }