From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Simmons Date: Tue, 11 Aug 2020 08:20:05 -0400 Subject: [lustre-devel] [PATCH 09/23] lustre: sec: check if page is empty with ZERO_PAGE In-Reply-To: <1597148419-20629-1-git-send-email-jsimmons@infradead.org> References: <1597148419-20629-1-git-send-email-jsimmons@infradead.org> Message-ID: <1597148419-20629-10-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: Sebastien Buisson In osc_brw_fini_request(), page needs decryption only if it is not empty. To check this, use ZERO_PAGE macro available for all architectures, and compare with memcmp. It will likely be faster/more efficient than comparing the words by hand as may use optimized CPU instructions or ASM code. WC-bug-id: https://jira.whamcloud.com/browse/LU-12275 Lustre-commit: 45c26bc11b7b1e ("LU-12275 sec: check if page is empty with ZERO_PAGE") Signed-off-by: Sebastien Buisson Reviewed-on: https://review.whamcloud.com/38918 Reviewed-by: Andreas Dilger Reviewed-by: James Simmons Reviewed-by: Mike Pershin Reviewed-by: Oleg Drokin Signed-off-by: James Simmons --- fs/lustre/osc/osc_request.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/fs/lustre/osc/osc_request.c b/fs/lustre/osc/osc_request.c index 1968d62..3bbe3d9 100644 --- a/fs/lustre/osc/osc_request.c +++ b/fs/lustre/osc/osc_request.c @@ -2075,16 +2075,11 @@ static int osc_brw_fini_request(struct ptlrpc_request *req, int rc) } for (idx = 0; idx < aa->aa_page_count; idx++) { struct brw_page *pg = aa->aa_ppga[idx]; - u64 *p, *q; /* do not decrypt if page is all 0s */ - p = q = page_address(pg->pg); - while (p - q < PAGE_SIZE / sizeof(*p)) { - if (*p != 0) - break; - p++; - } - if (p - q == PAGE_SIZE / sizeof(*p)) { + if (memcmp(page_address(pg->pg), + page_address(ZERO_PAGE(0)), + PAGE_SIZE) == 0) { /* if page is empty forward info to upper layers * (ll_io_zero_page) by clearing PagePrivate2 */ -- 1.8.3.1