block: clean up blkdev_get() wrappers and their users

After recent blkdev_get() modifications, open_by_devnum() and
open_bdev_exclusive() are simple wrappers around blkdev_get().
Replace them with blkdev_get_by_dev() and blkdev_get_by_path().

blkdev_get_by_dev() is identical to open_by_devnum().
blkdev_get_by_path() is slightly different in that it doesn't
automatically add %FMODE_EXCL to @mode.

All users are converted.  Most conversions are mechanical and don't
introduce any behavior difference.  There are several exceptions.

* btrfs now sets FMODE_EXCL in btrfs_device->mode, so there's no
  reason to OR it explicitly on blkdev_put().

* gfs2, nilfs2 and the generic mount_bdev() now set FMODE_EXCL in
  sb->s_mode.

* With the above changes, sb->s_mode now always should contain
  FMODE_EXCL.  WARN_ON_ONCE() added to kill_block_super() to detect
  errors.

The new blkdev_get_*() functions are with proper docbook comments.
While at it, add function description to blkdev_get() too.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Joern Engel <joern@lazybastard.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: reiserfs-devel@vger.kernel.org
Cc: xfs-masters@oss.sgi.com
Cc: Alexander Viro <viro@zeniv.linux.org.uk>

2 files changed, 15 insertions, 11 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f1b729d3b883..95324e9f9280 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -489,7 +489,7 @@ again:
                         continue;
 
                 if (device->bdev) {
-                        blkdev_put(device->bdev, device->mode | FMODE_EXCL);
+                        blkdev_put(device->bdev, device->mode);
                         device->bdev = NULL;
                         fs_devices->open_devices--;
                 }
@@ -523,7 +523,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 
         list_for_each_entry(device, &fs_devices->devices, dev_list) {
                 if (device->bdev) {
-                        blkdev_put(device->bdev, device->mode | FMODE_EXCL);
+                        blkdev_put(device->bdev, device->mode);
                         fs_devices->open_devices--;
                 }
                 if (device->writeable) {
@@ -580,13 +580,15 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
         int seeding = 1;
         int ret = 0;
 
+        flags |= FMODE_EXCL;
+
         list_for_each_entry(device, head, dev_list) {
                 if (device->bdev)
                         continue;
                 if (!device->name)
                         continue;
 
-                bdev = open_bdev_exclusive(device->name, flags, holder);
+                bdev = blkdev_get_by_path(device->name, flags, holder);
                 if (IS_ERR(bdev)) {
                         printk(KERN_INFO "open %s failed\n", device->name);
                         goto error;
@@ -638,7 +640,7 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 error_brelse:
                 brelse(bh);
 error_close:
-                blkdev_put(bdev, flags | FMODE_EXCL);
+                blkdev_put(bdev, flags);
 error:
                 continue;
         }
@@ -684,7 +686,8 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 
         mutex_lock(&uuid_mutex);
 
-        bdev = open_bdev_exclusive(path, flags, holder);
+        flags |= FMODE_EXCL;
+        bdev = blkdev_get_by_path(path, flags, holder);
 
         if (IS_ERR(bdev)) {
                 ret = PTR_ERR(bdev);
@@ -716,7 +719,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
 
         brelse(bh);
 error_close:
-        blkdev_put(bdev, flags | FMODE_EXCL);
+        blkdev_put(bdev, flags);
 error:
         mutex_unlock(&uuid_mutex);
         return ret;
@@ -1179,8 +1182,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                         goto out;
                 }
         } else {
-                bdev = open_bdev_exclusive(device_path, FMODE_READ,
-                                      root->fs_info->bdev_holder);
+                bdev = blkdev_get_by_path(device_path, FMODE_READ | FMODE_EXCL,
+                                          root->fs_info->bdev_holder);
                 if (IS_ERR(bdev)) {
                         ret = PTR_ERR(bdev);
                         goto out;
@@ -1244,7 +1247,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                 root->fs_info->fs_devices->latest_bdev = next_device->bdev;
 
         if (device->bdev) {
-                blkdev_put(device->bdev, device->mode | FMODE_EXCL);
+                blkdev_put(device->bdev, device->mode);
                 device->bdev = NULL;
                 device->fs_devices->open_devices--;
         }
@@ -1439,7 +1442,8 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
                 return -EINVAL;
 
-        bdev = open_bdev_exclusive(device_path, 0, root->fs_info->bdev_holder);
+        bdev = blkdev_get_by_path(device_path, FMODE_EXCL,
+                                  root->fs_info->bdev_holder);
         if (IS_ERR(bdev))
                 return PTR_ERR(bdev);
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 2b638b6e4eea..856e75770304 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -49,7 +49,7 @@ struct btrfs_device {
 
         struct block_device *bdev;
 
-        /* the mode sent to open_bdev_exclusive */
+        /* the mode sent to blkdev_get */
         fmode_t mode;
 
         char *name;