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authorJan Kara <jack@suse.cz>2020-09-04 11:58:52 +0300
committerJens Axboe <axboe@kernel.dk>2020-09-08 05:10:55 +0300
commit384d87ef2c954fc58e6c5fd8253e4a1984f5fe02 (patch)
treebc6217832a737ad90b255e09721b478afc24f7b5 /include/linux/blkdev.h
parent6dbf7bb555981fb5faf7b691e8f6169fc2b2e63b (diff)
downloadlinux-384d87ef2c954fc58e6c5fd8253e4a1984f5fe02.tar.xz
block: Do not discard buffers under a mounted filesystem
Discarding blocks and buffers under a mounted filesystem is hardly anything admin wants to do. Usually it will confuse the filesystem and sometimes the loss of buffer_head state (including b_private field) can even cause crashes like: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 PGD 0 P4D 0 Oops: 0002 [#1] SMP PTI CPU: 4 PID: 203778 Comm: jbd2/dm-3-8 Kdump: loaded Tainted: G O --------- - - 4.18.0-147.5.0.5.h126.eulerosv2r9.x86_64 #1 Hardware name: Huawei RH2288H V3/BC11HGSA0, BIOS 1.57 08/11/2015 RIP: 0010:jbd2_journal_grab_journal_head+0x1b/0x40 [jbd2] ... Call Trace: __jbd2_journal_insert_checkpoint+0x23/0x70 [jbd2] jbd2_journal_commit_transaction+0x155f/0x1b60 [jbd2] kjournald2+0xbd/0x270 [jbd2] So if we don't have block device open with O_EXCL already, claim the block device while we truncate buffer cache. This makes sure any exclusive block device user (such as filesystem) cannot operate on the device while we are discarding buffer cache. Reported-by: Ye Bin <yebin10@huawei.com> Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> [axboe: fix !CONFIG_BLOCK error in truncate_bdev_range()] Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/blkdev.h')
-rw-r--r--include/linux/blkdev.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7d82959e7b86..37ec5a73d027 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1987,11 +1987,18 @@ void bdput(struct block_device *);
#ifdef CONFIG_BLOCK
void invalidate_bdev(struct block_device *bdev);
+int truncate_bdev_range(struct block_device *bdev, fmode_t mode, loff_t lstart,
+ loff_t lend);
int sync_blockdev(struct block_device *bdev);
#else
static inline void invalidate_bdev(struct block_device *bdev)
{
}
+static inline int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
+ loff_t lstart, loff_t lend)
+{
+ return 0;
+}
static inline int sync_blockdev(struct block_device *bdev)
{
return 0;