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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 /block | |
| 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 'block')
| -rw-r--r-- | block/blk-core.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index d2bba4700e652..6375674e719ba 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -110,14 +110,12 @@ void blk_queue_congestion_threshold(struct request_queue *q) * @bdev: device * * Locates the passed device's request queue and returns the address of its - * backing_dev_info. This function can only be called if @bdev is opened - * and the return value is never NULL. + * backing_dev_info. The return value is never NULL however we may return + * &noop_backing_dev_info if the bdev is not currently open. */ struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) { - struct request_queue *q = bdev_get_queue(bdev); - - return q->backing_dev_info; + return bdev->bd_bdi; } EXPORT_SYMBOL(blk_get_backing_dev_info); |