1 files changed, 31 insertions, 0 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index b957717e25ab..b3c1efff5e1d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -285,6 +285,8 @@ static void init_once(void *foo)
         INIT_LIST_HEAD(&bdev->bd_holder_list);
 #endif
         inode_init_once(&ei->vfs_inode);
+        /* Initialize mutex for freeze. */
+        mutex_init(&bdev->bd_fsfreeze_mutex);
 }
 
 static inline void __bd_forget(struct inode *inode)
@@ -1005,6 +1007,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
         }
 
         lock_kernel();
+ restart:
 
         ret = -ENXIO;
         disk = get_gendisk(bdev->bd_dev, &partno);
@@ -1025,6 +1028,19 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 
                         if (disk->fops->open) {
                                 ret = disk->fops->open(bdev, mode);
+                                if (ret == -ERESTARTSYS) {
+                                        /* Lost a race with 'disk' being
+                                         * deleted, try again.
+                                         * See md.c
+                                         */
+                                        disk_put_part(bdev->bd_part);
+                                        bdev->bd_part = NULL;
+                                        module_put(disk->fops->owner);
+                                        put_disk(disk);
+                                        bdev->bd_disk = NULL;
+                                        mutex_unlock(&bdev->bd_mutex);
+                                        goto restart;
+                                }
                                 if (ret)
                                         goto out_clear;
                         }
@@ -1220,6 +1236,20 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
         return blkdev_ioctl(bdev, mode, cmd, arg);
 }
 
+/*
+ * Try to release a page associated with block device when the system
+ * is under memory pressure.
+ */
+static int blkdev_releasepage(struct page *page, gfp_t wait)
+{
+        struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
+
+        if (super && super->s_op->bdev_try_to_free_page)
+                return super->s_op->bdev_try_to_free_page(super, page, wait);
+
+        return try_to_free_buffers(page);
+}
+
 static const struct address_space_operations def_blk_aops = {
         .readpage       = blkdev_readpage,
         .writepage      = blkdev_writepage,
@@ -1227,6 +1257,7 @@ static const struct address_space_operations def_blk_aops = {
         .write_begin    = blkdev_write_begin,
         .write_end      = blkdev_write_end,
         .writepages     = generic_writepages,
+        .releasepage    = blkdev_releasepage,
         .direct_IO      = blkdev_direct_IO,
 };