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Date: Thu, 10 Aug 2023 12:20:56 +0200
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu,
adilger.kernel@...ger.ca, jack@...e.cz, yi.zhang@...wei.com,
yukuai3@...wei.com
Subject: Re: [PATCH v2 11/12] ext4: cleanup ext4_get_dev_journal() and
ext4_get_journal()
On Thu 10-08-23 16:54:16, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
>
> Factor out a new helper form ext4_get_dev_journal() to get external
> journal bdev and check validation of this device, drop ext4_blkdev_get()
> helper, and also remove duplicate check of journal feature. It makes
> ext4_get_dev_journal() more clear than before.
>
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
Just one nit: We have ext4_get_dev_journal() function and now you create
ext4_get_journal_dev() helper. These are confusingly similar names. So I
suggest you rename the new helper to something like
ext4_get_journal_blkdev() to make the difference clearer. Otherwise feel
free to add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> fs/ext4/super.c | 109 ++++++++++++++++++++++--------------------------
> 1 file changed, 49 insertions(+), 60 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index ce2e02b139af..2f71076f678a 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1105,26 +1105,6 @@ static const struct blk_holder_ops ext4_holder_ops = {
> .mark_dead = ext4_bdev_mark_dead,
> };
>
> -/*
> - * Open the external journal device
> - */
> -static struct block_device *ext4_blkdev_get(dev_t dev, struct super_block *sb)
> -{
> - struct block_device *bdev;
> -
> - bdev = blkdev_get_by_dev(dev, BLK_OPEN_READ | BLK_OPEN_WRITE, sb,
> - &ext4_holder_ops);
> - if (IS_ERR(bdev))
> - goto fail;
> - return bdev;
> -
> -fail:
> - ext4_msg(sb, KERN_ERR,
> - "failed to open journal device unknown-block(%u,%u) %ld",
> - MAJOR(dev), MINOR(dev), PTR_ERR(bdev));
> - return NULL;
> -}
> -
> /*
> * Release the journal device
> */
> @@ -5780,14 +5760,14 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb,
> ext4_msg(sb, KERN_ERR, "journal inode is deleted");
> return NULL;
> }
> -
> - ext4_debug("Journal inode found at %p: %lld bytes\n",
> - journal_inode, journal_inode->i_size);
> if (!S_ISREG(journal_inode->i_mode) || IS_ENCRYPTED(journal_inode)) {
> ext4_msg(sb, KERN_ERR, "invalid journal inode");
> iput(journal_inode);
> return NULL;
> }
> +
> + ext4_debug("Journal inode found at %p: %lld bytes\n",
> + journal_inode, journal_inode->i_size);
> return journal_inode;
> }
>
> @@ -5819,9 +5799,6 @@ static journal_t *ext4_get_journal(struct super_block *sb,
> struct inode *journal_inode;
> journal_t *journal;
>
> - if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
> - return NULL;
> -
> journal_inode = ext4_get_journal_inode(sb, journal_inum);
> if (!journal_inode)
> return NULL;
> @@ -5838,25 +5815,25 @@ static journal_t *ext4_get_journal(struct super_block *sb,
> return journal;
> }
>
> -static journal_t *ext4_get_dev_journal(struct super_block *sb,
> - dev_t j_dev)
> +static struct block_device *ext4_get_journal_dev(struct super_block *sb,
> + dev_t j_dev, ext4_fsblk_t *j_start,
> + ext4_fsblk_t *j_len)
> {
> struct buffer_head *bh;
> - journal_t *journal;
> - ext4_fsblk_t start;
> - ext4_fsblk_t len;
> + struct block_device *bdev;
> int hblock, blocksize;
> ext4_fsblk_t sb_block;
> unsigned long offset;
> struct ext4_super_block *es;
> - struct block_device *bdev;
>
> - if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
> - return NULL;
> -
> - bdev = ext4_blkdev_get(j_dev, sb);
> - if (bdev == NULL)
> + bdev = blkdev_get_by_dev(j_dev, BLK_OPEN_READ | BLK_OPEN_WRITE, sb,
> + &ext4_holder_ops);
> + if (IS_ERR(bdev)) {
> + ext4_msg(sb, KERN_ERR,
> + "failed to open journal device unknown-block(%u,%u) %ld",
> + MAJOR(j_dev), MINOR(j_dev), PTR_ERR(bdev));
> return NULL;
> + }
>
> blocksize = sb->s_blocksize;
> hblock = bdev_logical_block_size(bdev);
> @@ -5869,7 +5846,8 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
> sb_block = EXT4_MIN_BLOCK_SIZE / blocksize;
> offset = EXT4_MIN_BLOCK_SIZE % blocksize;
> set_blocksize(bdev, blocksize);
> - if (!(bh = __bread(bdev, sb_block, blocksize))) {
> + bh = __bread(bdev, sb_block, blocksize);
> + if (!bh) {
> ext4_msg(sb, KERN_ERR, "couldn't read superblock of "
> "external journal");
> goto out_bdev;
> @@ -5879,56 +5857,67 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
> if ((le16_to_cpu(es->s_magic) != EXT4_SUPER_MAGIC) ||
> !(le32_to_cpu(es->s_feature_incompat) &
> EXT4_FEATURE_INCOMPAT_JOURNAL_DEV)) {
> - ext4_msg(sb, KERN_ERR, "external journal has "
> - "bad superblock");
> - brelse(bh);
> - goto out_bdev;
> + ext4_msg(sb, KERN_ERR, "external journal has bad superblock");
> + goto out_bh;
> }
>
> if ((le32_to_cpu(es->s_feature_ro_compat) &
> EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
> es->s_checksum != ext4_superblock_csum(sb, es)) {
> - ext4_msg(sb, KERN_ERR, "external journal has "
> - "corrupt superblock");
> - brelse(bh);
> - goto out_bdev;
> + ext4_msg(sb, KERN_ERR, "external journal has corrupt superblock");
> + goto out_bh;
> }
>
> if (memcmp(EXT4_SB(sb)->s_es->s_journal_uuid, es->s_uuid, 16)) {
> ext4_msg(sb, KERN_ERR, "journal UUID does not match");
> - brelse(bh);
> - goto out_bdev;
> + goto out_bh;
> }
>
> - len = ext4_blocks_count(es);
> - start = sb_block + 1;
> - brelse(bh); /* we're done with the superblock */
> + *j_start = sb_block + 1;
> + *j_len = ext4_blocks_count(es);
> + brelse(bh);
> + return bdev;
> +
> +out_bh:
> + brelse(bh);
> +out_bdev:
> + blkdev_put(bdev, sb);
> + return NULL;
> +}
> +
> +static journal_t *ext4_get_dev_journal(struct super_block *sb,
> + dev_t j_dev)
> +{
> + journal_t *journal;
> + ext4_fsblk_t j_start;
> + ext4_fsblk_t j_len;
> + struct block_device *journal_bdev;
> +
> + journal_bdev = ext4_get_journal_dev(sb, j_dev, &j_start, &j_len);
> + if (!journal_bdev)
> + return NULL;
>
> - journal = jbd2_journal_init_dev(bdev, sb->s_bdev,
> - start, len, blocksize);
> + journal = jbd2_journal_init_dev(journal_bdev, sb->s_bdev, j_start,
> + j_len, sb->s_blocksize);
> if (IS_ERR(journal)) {
> ext4_msg(sb, KERN_ERR, "failed to create device journal");
> goto out_bdev;
> }
> - journal->j_private = sb;
> - if (ext4_read_bh_lock(journal->j_sb_buffer, REQ_META | REQ_PRIO, true)) {
> - ext4_msg(sb, KERN_ERR, "I/O error on journal device");
> - goto out_journal;
> - }
> if (be32_to_cpu(journal->j_superblock->s_nr_users) != 1) {
> ext4_msg(sb, KERN_ERR, "External journal has more than one "
> "user (unsupported) - %d",
> be32_to_cpu(journal->j_superblock->s_nr_users));
> goto out_journal;
> }
> - EXT4_SB(sb)->s_journal_bdev = bdev;
> + journal->j_private = sb;
> + EXT4_SB(sb)->s_journal_bdev = journal_bdev;
> ext4_init_journal_params(sb, journal);
> return journal;
>
> out_journal:
> jbd2_journal_destroy(journal);
> out_bdev:
> - blkdev_put(bdev, sb);
> + blkdev_put(journal_bdev, sb);
> return NULL;
> }
>
> --
> 2.34.3
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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