powerpc: iomap.c: introduce io{read|write}64_{lo_hi|hi_lo}

[linux.git] / fs / block_dev.c

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 4a181fcb51751dc2cbc8fda10930a47bc883380e..fe09ef9c21f349a55d31261b5dd416b1bde2a3aa 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1058,6 +1058,27 @@ static int bd_prepare_to_claim(struct block_device *bdev,
        return 0;
 }
 
+static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
+{
+       struct gendisk *disk = get_gendisk(bdev->bd_dev, partno);
+
+       if (!disk)
+               return NULL;
+       /*
+        * Now that we hold gendisk reference we make sure bdev we looked up is
+        * not stale. If it is, it means device got removed and created before
+        * we looked up gendisk and we fail open in such case. Associating
+        * unhashed bdev with newly created gendisk could lead to two bdevs
+        * (and thus two independent caches) being associated with one device
+        * which is bad.
+        */
+       if (inode_unhashed(bdev->bd_inode)) {
+               put_disk_and_module(disk);
+               return NULL;
+       }
+       return disk;
+}
+
 /**
  * bd_start_claiming - start claiming a block device
  * @bdev: block device of interest
@@ -1094,7 +1115,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
         * @bdev might not have been initialized properly yet, look up
         * and grab the outer block device the hard way.
         */
-       disk = get_gendisk(bdev->bd_dev, &partno);
+       disk = bdev_get_gendisk(bdev, &partno);
        if (!disk)
                return ERR_PTR(-ENXIO);
 
@@ -1111,8 +1132,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
        else
                whole = bdgrab(bdev);
 
-       module_put(disk->fops->owner);
-       put_disk(disk);
+       put_disk_and_module(disk);
        if (!whole)
                return ERR_PTR(-ENOMEM);
 
@@ -1407,10 +1427,10 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
 static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 {
        struct gendisk *disk;
-       struct module *owner;
        int ret;
        int partno;
        int perm = 0;
+       bool first_open = false;
 
        if (mode & FMODE_READ)
                perm |= MAY_READ;
@@ -1430,14 +1450,14 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
  restart:
 
        ret = -ENXIO;
-       disk = get_gendisk(bdev->bd_dev, &partno);
+       disk = bdev_get_gendisk(bdev, &partno);
        if (!disk)
                goto out;
-       owner = disk->fops->owner;
 
        disk_block_events(disk);
        mutex_lock_nested(&bdev->bd_mutex, for_part);
        if (!bdev->bd_openers) {
+               first_open = true;
                bdev->bd_disk = disk;
                bdev->bd_queue = disk->queue;
                bdev->bd_contains = bdev;
@@ -1463,8 +1483,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                                        bdev->bd_queue = NULL;
                                        mutex_unlock(&bdev->bd_mutex);
                                        disk_unblock_events(disk);
-                                       put_disk(disk);
-                                       module_put(owner);
+                                       put_disk_and_module(disk);
                                        goto restart;
                                }
                        }
@@ -1524,15 +1543,15 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                        if (ret)
                                goto out_unlock_bdev;
                }
-               /* only one opener holds refs to the module and disk */
-               put_disk(disk);
-               module_put(owner);
        }
        bdev->bd_openers++;
        if (for_part)
                bdev->bd_part_count++;
        mutex_unlock(&bdev->bd_mutex);
        disk_unblock_events(disk);
+       /* only one opener holds refs to the module and disk */
+       if (!first_open)
+               put_disk_and_module(disk);
        return 0;
 
  out_clear:
@@ -1546,8 +1565,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
  out_unlock_bdev:
        mutex_unlock(&bdev->bd_mutex);
        disk_unblock_events(disk);
-       put_disk(disk);
-       module_put(owner);
+       put_disk_and_module(disk);
  out:
        bdput(bdev);
 
@@ -1770,8 +1788,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
                        disk->fops->release(disk, mode);
        }
        if (!bdev->bd_openers) {
-               struct module *owner = disk->fops->owner;
-
                disk_put_part(bdev->bd_part);
                bdev->bd_part = NULL;
                bdev->bd_disk = NULL;
@@ -1779,8 +1795,7 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
                        victim = bdev->bd_contains;
                bdev->bd_contains = NULL;
 
-               put_disk(disk);
-               module_put(owner);
+               put_disk_and_module(disk);
        }
        mutex_unlock(&bdev->bd_mutex);
        bdput(bdev);