[PATCH 4.9 83/96] fs: ratelimit __find_get_block_slow() failure message.

Greg Kroah-Hartman
2019-03-12T17:18:59Z

[ Upstream commit 43636c804df0126da669c261fc820fb22f62bfc2 ]

When something let __find_get_block_slow() hit all_mapped path, it calls
printk() for 100+ times per a second. But there is no need to print same
message with such high frequency; it is just asking for stall warning, or
at least bloating log files.

[ 399.866302][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
[ 399.873324][T15342] b_state=0x00000029, b_size=512
[ 399.878403][T15342] device loop0 blocksize: 4096
[ 399.883296][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
[ 399.890400][T15342] b_state=0x00000029, b_size=512
[ 399.895595][T15342] device loop0 blocksize: 4096
[ 399.900556][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
[ 399.907471][T15342] b_state=0x00000029, b_size=512
[ 399.912506][T15342] device loop0 blocksize: 4096

This patch reduces frequency to up to once per a second, in addition to
concatenating three lines into one.

[ 399.866302][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8, b_state=0x00000029, b_size=512, device loop0 blocksize: 4096

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/buffer.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 5d8f496d624e..e0d46d47e358 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -207,6 +207,7 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
struct buffer_head *head;
struct page *page;
int all_mapped = 1;
+ static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1);

index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED);
@@ -234,15 +235,15 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
* file io on the block device and getblk. It gets dealt with
* elsewhere, don't buffer_error if we had some unmapped buffers
*/
- if (all_mapped) {
- printk("__find_get_block_slow() failed. "
- "block=%llu, b_blocknr=%llu\n",
- (unsigned long long)block,
- (unsigned long long)bh->b_blocknr);
- printk("b_state=0x%08lx, b_size=%zu\n",
- bh->b_state, bh->b_size);
- printk("device %pg blocksize: %d\n", bdev,
- 1 << bd_inode->i_blkbits);
+ ratelimit_set_flags(&last_warned, RATELIMIT_MSG_ON_RELEASE);
+ if (all_mapped && __ratelimit(&last_warned)) {
+ printk("__find_get_block_slow() failed. block=%llu, "
+ "b_blocknr=%llu, b_state=0x%08lx, b_size=%zu, "
+ "device %pg blocksize: %d\n",
+ (unsigned long long)block,
+ (unsigned long long)bh->b_blocknr,
+ bh->b_state, bh->b_size, bdev,
+ 1 << bd_inode->i_blkbits);
}
out_unlock:
spin_unlock(&bd_mapping->private_lock);
--
2.19.1