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| author | Jan Kara <jack@suse.cz> | 2017-02-02 15:56:52 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-02-02 08:20:53 -0700 |
| commit | b1d2dc5659b41741f5a29b2ade76ffb4e5bb13d8 (patch) | |
| tree | 6f01d065b95e5d7a94a26d3892142db6ea60dae5 /fs | |
| parent | d03f6cdc1fc422accb734c7c07a661a0018d8631 (diff) | |
| download | linux-0-day-b1d2dc5659b41741f5a29b2ade76ffb4e5bb13d8.tar.gz linux-0-day-b1d2dc5659b41741f5a29b2ade76ffb4e5bb13d8.tar.xz | |
block: Make blk_get_backing_dev_info() safe without open bdev
Currenly blk_get_backing_dev_info() is not safe to be called when the
block device is not open as bdev->bd_disk is NULL in that case. However
inode_to_bdi() uses this function and may be call called from flusher
worker or other writeback related functions without bdev being open
which leads to crashes such as:
[113031.075540] Unable to handle kernel paging request for data at address 0x00000000
[113031.075614] Faulting instruction address: 0xc0000000003692e0
0:mon> t
[c0000000fb65f900] c00000000036cb6c writeback_sb_inodes+0x30c/0x590
[c0000000fb65fa10] c00000000036ced4 __writeback_inodes_wb+0xe4/0x150
[c0000000fb65fa70] c00000000036d33c wb_writeback+0x30c/0x450
[c0000000fb65fb40] c00000000036e198 wb_workfn+0x268/0x580
[c0000000fb65fc50] c0000000000f3470 process_one_work+0x1e0/0x590
[c0000000fb65fce0] c0000000000f38c8 worker_thread+0xa8/0x660
[c0000000fb65fd80] c0000000000fc4b0 kthread+0x110/0x130
[c0000000fb65fe30] c0000000000098f0 ret_from_kernel_thread+0x5c/0x6c
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/block_dev.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index ed6a34be7a1ef..601b71b76d7fb 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -884,6 +884,8 @@ static void bdev_evict_inode(struct inode *inode) spin_lock(&bdev_lock); list_del_init(&bdev->bd_list); spin_unlock(&bdev_lock); + if (bdev->bd_bdi != &noop_backing_dev_info) + bdi_put(bdev->bd_bdi); } static const struct super_operations bdev_sops = { @@ -986,6 +988,7 @@ struct block_device *bdget(dev_t dev) bdev->bd_contains = NULL; bdev->bd_super = NULL; bdev->bd_inode = inode; + bdev->bd_bdi = &noop_backing_dev_info; bdev->bd_block_size = (1 << inode->i_blkbits); bdev->bd_part_count = 0; bdev->bd_invalidated = 0; @@ -1542,6 +1545,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bdev->bd_disk = disk; bdev->bd_queue = disk->queue; bdev->bd_contains = bdev; + if (bdev->bd_bdi == &noop_backing_dev_info) + bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info); if (!partno) { ret = -ENXIO; @@ -1637,6 +1642,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bdev->bd_disk = NULL; bdev->bd_part = NULL; bdev->bd_queue = NULL; + bdi_put(bdev->bd_bdi); + bdev->bd_bdi = &noop_backing_dev_info; if (bdev != bdev->bd_contains) __blkdev_put(bdev->bd_contains, mode, 1); bdev->bd_contains = NULL; |