linux-ext4 - [RFCv2 2/4] ext4: Optimize ext4_ext

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Message-Id: <597d295e3f667478de3e085800f7cdad75722823.1580121790.git.riteshh@linux.ibm.com>
Date:   Tue, 28 Jan 2020 15:48:26 +0530
From:   Ritesh Harjani <riteshh@...ux.ibm.com>
To:     jack@...e.cz, tytso@....edu, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, darrick.wong@...cle.com,
        hch@...radead.org, cmaiolino@...hat.com,
        Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: [RFCv2 2/4] ext4: Optimize ext4_ext_precache for 0 depth

This patch avoids the memory alloc & free path when depth is 0,
since anyway there is no extra caching done in that case.
So on checking depth 0, simply return early.

Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>
---
 fs/ext4/extents.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ee83fe7c98aa..0de548bb3c90 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -594,6 +594,12 @@ int ext4_ext_precache(struct inode *inode)
 	down_read(&ei->i_data_sem);
 	depth = ext_depth(inode);
 
+	/* Don't cache anything if there are no external extent blocks */
+	if (!depth) {
+		up_read(&ei->i_data_sem);
+		return ret;
+	}
+
 	path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
 		       GFP_NOFS);
 	if (path == NULL) {
@@ -601,9 +607,6 @@ int ext4_ext_precache(struct inode *inode)
 		return -ENOMEM;
 	}
 
-	/* Don't cache anything if there are no external extent blocks */
-	if (depth == 0)
-		goto out;
 	path[0].p_hdr = ext_inode_hdr(inode);
 	ret = ext4_ext_check(inode, path[0].p_hdr, depth, 0);
 	if (ret)
-- 
2.21.0