[PATCH -next 4/6] ext4: avoid to re-read mmp check data get from page cache
From: Ye Bin <hidden>
Date: 2021-09-06 14:38:09
Also in:
lkml
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
As call read_mmp_block pass bh_check which value is NULL, then call sb_getblk to get buffer_head. But mmp_block's buffer_head is already exist which also is uptodate. Lead to compare the same data. Signed-off-by: Ye Bin <redacted> --- fs/ext4/mmp.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-)
diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 0fe7b9ac9db6..2a1473e4a9de 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c@@ -213,10 +213,7 @@ static int kmmpd(void *data) * we need to check if the MMP block is as we write it. */ if (jiffies - last_check_time > mmp_check_interval * HZ) { - struct buffer_head *bh_check = NULL; - struct mmp_struct *mmp_check; - - retval = read_mmp_block(sb, &bh_check, mmp_block); + retval = read_mmp_block(sb, &bh, mmp_block); if (retval) { ext4_error_err(sb, -retval, "error reading MMP data: %d",
@@ -224,20 +221,18 @@ static int kmmpd(void *data) goto wait_to_exit; } - mmp_check = (struct mmp_struct *)(bh_check->b_data); - if (seq != mmp_check->mmp_seq || - memcmp(nodename, mmp_check->mmp_nodename, - sizeof(mmp->mmp_nodename))) { - dump_mmp_msg(sb, mmp_check, + mmp = (struct mmp_struct *)(bh->b_data); + if (seq != le32_to_cpu(mmp->mmp_seq) || + memcmp(nodename, mmp->mmp_nodename, + sizeof(nodename))) { + dump_mmp_msg(sb, mmp, "Error while updating MMP info. " "The filesystem seems to have been" " multiply mounted."); ext4_error_err(sb, EBUSY, "abort"); - put_bh(bh_check); retval = -EBUSY; goto wait_to_exit; } - put_bh(bh_check); last_check_time = jiffies; }
--
2.31.1