linux-kernel - [RFC v3 1/8] ext4: Stop searching if PA doesn't satisfy non-extent file

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Message-Id: <113e30014fdcf409680e20ec1ef4455ace33884d.1664269665.git.ojaswin@linux.ibm.com>
Date:   Tue, 27 Sep 2022 14:46:41 +0530
From:   Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To:     linux-ext4@...r.kernel.org, "Theodore Ts'o" <tytso@....edu>
Cc:     Ritesh Harjani <riteshh@...ux.ibm.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, rookxu <brookxu.cn@...il.com>,
        Ritesh Harjani <ritesh.list@...il.com>
Subject: [RFC v3 1/8] ext4: Stop searching if PA doesn't satisfy non-extent file

If we come across a PA that matches the logical offset but is unable to
satisfy a non-extent file due to its physical start being higher than
that supported by non extent files, then simply stop searching for
another PA and break out of loop. This is because, since PAs don't
overlap, we won't be able to find another inode PA which can satisfy the
original request.

Signed-off-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
---
 fs/ext4/mballoc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 71f5b67d7f28..2e3eb632a216 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4383,8 +4383,13 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 		/* non-extent files can't have physical blocks past 2^32 */
 		if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) &&
 		    (pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len) >
-		     EXT4_MAX_BLOCK_FILE_PHYS))
-			continue;
+		     EXT4_MAX_BLOCK_FILE_PHYS)) {
+			/*
+			 * Since PAs don't overlap, we won't find any
+			 * other PA to satisfy this.
+			 */
+			break;
+		}
 
 		/* found preallocated blocks, use them */
 		spin_lock(&pa->pa_lock);
-- 
2.31.1