From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Simmons Date: Mon, 25 May 2020 18:08:08 -0400 Subject: [lustre-devel] [PATCH 31/45] lustre: llite: fix possible divide zero in ll_use_fast_io() In-Reply-To: <1590444502-20533-1-git-send-email-jsimmons@infradead.org> References: <1590444502-20533-1-git-send-email-jsimmons@infradead.org> Message-ID: <1590444502-20533-32-git-send-email-jsimmons@infradead.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org From: Wang Shilong ll_use_fast_io() is used to check wheather we could use fast IO. Since it is called in fast path, we don't hold ras_lock to protect access, there might have the race @ras_stride_bytes is reset after stride_io_mode() check. Fixes: 52fa1b524a84 ("lustre: llite: try fast io for stride io correctly") WC-bug-id: https://jira.whamcloud.com/browse/LU-13541 Lustre-commit: 7cd0afe58321 ("LU-13541 llite: fix possible divide zero in ll_use_fast_io()") Signed-off-by: Wang Shilong Reviewed-on: https://review.whamcloud.com/38545 Reviewed-by: Andreas Dilger Tested-by: Andreas Dilger Reviewed-by: Jian Yu Reviewed-by: James Nunez Signed-off-by: James Simmons --- fs/lustre/llite/rw.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/lustre/llite/rw.c b/fs/lustre/llite/rw.c index 9e004f4..fd0bed6 100644 --- a/fs/lustre/llite/rw.c +++ b/fs/lustre/llite/rw.c @@ -1609,10 +1609,11 @@ static bool ll_use_fast_io(struct file *file, unsigned long fast_read_pages = max(RA_REMAIN_WINDOW_MIN, ras->ras_rpc_pages); loff_t skip_pages; + loff_t stride_bytes = ras->ras_stride_bytes; - if (stride_io_mode(ras)) { + if (stride_io_mode(ras) && stride_bytes) { skip_pages = (ras->ras_stride_length + - ras->ras_stride_bytes - 1) / ras->ras_stride_bytes; + ras->ras_stride_bytes - 1) / stride_bytes; skip_pages *= fast_read_pages; } else { skip_pages = fast_read_pages; -- 1.8.3.1