This patch is according to Jan Kara's suggestion: I guess I would just get rid of sb_getblk() in read_mmp_block() and always expect valid bh passed. The only place that passes NULL bh after this patch is one case in ext4_multi_mount_protect() and that can call sb_getblk() on its own. That way we can also simplify read_mmp_block() prototype to: static int read_mmp_block(struct super_block *sb, struct buffer_head *bh); Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx> --- fs/ext4/mmp.c | 40 +++++++++++++++------------------------- 1 file changed, 15 insertions(+), 25 deletions(-) diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c index 6ac6aacd8fa5..61c765c249b9 100644 --- a/fs/ext4/mmp.c +++ b/fs/ext4/mmp.c @@ -64,33 +64,26 @@ static int write_mmp_block(struct super_block *sb, struct buffer_head *bh) /* * Read the MMP block. It _must_ be read from disk and hence we clear the * uptodate flag on the buffer. + * Caller must ensure pass valid 'bh'. */ -static int read_mmp_block(struct super_block *sb, struct buffer_head **bh, - ext4_fsblk_t mmp_block) +static int read_mmp_block(struct super_block *sb, struct buffer_head *bh) { struct mmp_struct *mmp; int ret; - if (*bh) - clear_buffer_uptodate(*bh); - - /* This would be sb_bread(sb, mmp_block), except we need to be sure - * that the MD RAID device cache has been bypassed, and that the read - * is not blocked in the elevator. */ - if (!*bh) { - *bh = sb_getblk(sb, mmp_block); - if (!*bh) { - ret = -ENOMEM; - goto warn_exit; - } + if (!bh) { + ret = -EINVAL; + goto warn_exit; } - lock_buffer(*bh); - ret = ext4_read_bh(*bh, REQ_META | REQ_PRIO, NULL); + clear_buffer_uptodate(bh); + + lock_buffer(bh); + ret = ext4_read_bh(bh, REQ_META | REQ_PRIO, NULL); if (ret) goto warn_exit; - mmp = (struct mmp_struct *)((*bh)->b_data); + mmp = (struct mmp_struct *)((bh)->b_data); if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC) { ret = -EFSCORRUPTED; goto warn_exit; @@ -101,10 +94,7 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh, } return 0; warn_exit: - brelse(*bh); - *bh = NULL; - ext4_warning(sb, "Error %d while reading MMP block %llu", - ret, mmp_block); + ext4_warning(sb, "Error %d while reading MMP block", ret); return ret; } @@ -199,7 +189,7 @@ static int kmmpd(void *data) 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_check); if (retval) { ext4_error_err(sb, -retval, "error reading MMP data: %d", @@ -299,7 +289,7 @@ int ext4_multi_mount_protect(struct super_block *sb, if (bh) goto failed; - retval = read_mmp_block(sb, &bh, mmp_block); + retval = read_mmp_block(sb, bh); if (retval) goto failed; @@ -337,7 +327,7 @@ int ext4_multi_mount_protect(struct super_block *sb, goto failed; } - retval = read_mmp_block(sb, &bh, mmp_block); + retval = read_mmp_block(sb, bh); if (retval) goto failed; mmp = (struct mmp_struct *)(bh->b_data); @@ -366,7 +356,7 @@ int ext4_multi_mount_protect(struct super_block *sb, goto failed; } - retval = read_mmp_block(sb, &bh, mmp_block); + retval = read_mmp_block(sb, bh); if (retval) goto failed; mmp = (struct mmp_struct *)(bh->b_data); -- 2.31.1