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Message-ID: <20210810142722.923175-3-yi.zhang@huawei.com>
Date: Tue, 10 Aug 2021 22:27:21 +0800
From: Zhang Yi <yi.zhang@...wei.com>
To: <linux-ext4@...r.kernel.org>
CC: <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
<yi.zhang@...wei.com>, <yukuai3@...wei.com>
Subject: [PATCH 2/3] ext4: remove an unnecessary if statement in __ext4_get_inode_loc()
The "if (!buffer_uptodate(bh))" hunk covered almost the whole code after
getting buffer in __ext4_get_inode_loc() which seems unnecessary, remove
it and switch to check ext4_buffer_uptodate(), it simplify code and make
it more readable.
Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
fs/ext4/inode.c | 162 +++++++++++++++++++++++-------------------------
1 file changed, 78 insertions(+), 84 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index eb2526a35254..eae1b2d0b550 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4330,99 +4330,93 @@ static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
bh = sb_getblk(sb, block);
if (unlikely(!bh))
return -ENOMEM;
- if (!buffer_uptodate(bh)) {
- lock_buffer(bh);
-
- if (ext4_buffer_uptodate(bh)) {
- /* someone brought it uptodate while we waited */
- unlock_buffer(bh);
- goto has_buffer;
- }
+ if (ext4_buffer_uptodate(bh))
+ goto has_buffer;
- /*
- * If we have all information of the inode in memory and this
- * is the only valid inode in the block, we need not read the
- * block.
- */
- if (in_mem) {
- struct buffer_head *bitmap_bh;
- int i, start;
+ lock_buffer(bh);
+ /*
+ * If we have all information of the inode in memory and this
+ * is the only valid inode in the block, we need not read the
+ * block.
+ */
+ if (in_mem) {
+ struct buffer_head *bitmap_bh;
+ int i, start;
- start = inode_offset & ~(inodes_per_block - 1);
+ start = inode_offset & ~(inodes_per_block - 1);
- /* Is the inode bitmap in cache? */
- bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
- if (unlikely(!bitmap_bh))
- goto make_io;
+ /* Is the inode bitmap in cache? */
+ bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
+ if (unlikely(!bitmap_bh))
+ goto make_io;
- /*
- * If the inode bitmap isn't in cache then the
- * optimisation may end up performing two reads instead
- * of one, so skip it.
- */
- if (!buffer_uptodate(bitmap_bh)) {
- brelse(bitmap_bh);
- goto make_io;
- }
- for (i = start; i < start + inodes_per_block; i++) {
- if (i == inode_offset)
- continue;
- if (ext4_test_bit(i, bitmap_bh->b_data))
- break;
- }
+ /*
+ * If the inode bitmap isn't in cache then the
+ * optimisation may end up performing two reads instead
+ * of one, so skip it.
+ */
+ if (!buffer_uptodate(bitmap_bh)) {
brelse(bitmap_bh);
- if (i == start + inodes_per_block) {
- /* all other inodes are free, so skip I/O */
- memset(bh->b_data, 0, bh->b_size);
- set_buffer_uptodate(bh);
- unlock_buffer(bh);
- goto has_buffer;
- }
+ goto make_io;
+ }
+ for (i = start; i < start + inodes_per_block; i++) {
+ if (i == inode_offset)
+ continue;
+ if (ext4_test_bit(i, bitmap_bh->b_data))
+ break;
}
+ brelse(bitmap_bh);
+ if (i == start + inodes_per_block) {
+ /* all other inodes are free, so skip I/O */
+ memset(bh->b_data, 0, bh->b_size);
+ set_buffer_uptodate(bh);
+ unlock_buffer(bh);
+ goto has_buffer;
+ }
+ }
make_io:
- /*
- * If we need to do any I/O, try to pre-readahead extra
- * blocks from the inode table.
- */
- blk_start_plug(&plug);
- if (EXT4_SB(sb)->s_inode_readahead_blks) {
- ext4_fsblk_t b, end, table;
- unsigned num;
- __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
-
- table = ext4_inode_table(sb, gdp);
- /* s_inode_readahead_blks is always a power of 2 */
- b = block & ~((ext4_fsblk_t) ra_blks - 1);
- if (table > b)
- b = table;
- end = b + ra_blks;
- num = EXT4_INODES_PER_GROUP(sb);
- if (ext4_has_group_desc_csum(sb))
- num -= ext4_itable_unused_count(sb, gdp);
- table += num / inodes_per_block;
- if (end > table)
- end = table;
- while (b <= end)
- ext4_sb_breadahead_unmovable(sb, b++);
- }
+ /*
+ * If we need to do any I/O, try to pre-readahead extra
+ * blocks from the inode table.
+ */
+ blk_start_plug(&plug);
+ if (EXT4_SB(sb)->s_inode_readahead_blks) {
+ ext4_fsblk_t b, end, table;
+ unsigned num;
+ __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
+
+ table = ext4_inode_table(sb, gdp);
+ /* s_inode_readahead_blks is always a power of 2 */
+ b = block & ~((ext4_fsblk_t) ra_blks - 1);
+ if (table > b)
+ b = table;
+ end = b + ra_blks;
+ num = EXT4_INODES_PER_GROUP(sb);
+ if (ext4_has_group_desc_csum(sb))
+ num -= ext4_itable_unused_count(sb, gdp);
+ table += num / inodes_per_block;
+ if (end > table)
+ end = table;
+ while (b <= end)
+ ext4_sb_breadahead_unmovable(sb, b++);
+ }
- /*
- * There are other valid inodes in the buffer, this inode
- * has in-inode xattrs, or we don't have this inode in memory.
- * Read the block from disk.
- */
- trace_ext4_load_inode(sb, ino);
- ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO, NULL);
- blk_finish_plug(&plug);
- wait_on_buffer(bh);
- ext4_simulate_fail_bh(sb, bh, EXT4_SIM_INODE_EIO);
- if (!buffer_uptodate(bh)) {
- if (ret_block)
- *ret_block = block;
- brelse(bh);
- return -EIO;
- }
+ /*
+ * There are other valid inodes in the buffer, this inode
+ * has in-inode xattrs, or we don't have this inode in memory.
+ * Read the block from disk.
+ */
+ trace_ext4_load_inode(sb, ino);
+ ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO, NULL);
+ blk_finish_plug(&plug);
+ wait_on_buffer(bh);
+ ext4_simulate_fail_bh(sb, bh, EXT4_SIM_INODE_EIO);
+ if (!buffer_uptodate(bh)) {
+ if (ret_block)
+ *ret_block = block;
+ brelse(bh);
+ return -EIO;
}
has_buffer:
iloc->bh = bh;
--
2.31.1
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