jbd2: rename j_maxlen to j_total_len and add jbd2_journal_max_txn_bufs

The on-disk superblock field sb->s_maxlen represents the total size of
the journal including the fast commit area and is no more the max
number of blocks available for a transaction. The maximum number of
blocks available to a transaction is reduced by the number of fast
commit blocks. So, this patch renames j_maxlen to j_total_len to
better represent its intent. Also, it adds a function to calculate max
number of bufs available for a transaction.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201106035911.1942128-6-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/fsmap.c b/fs/ext4/fsmap.c
index b232c27..4c2a9fe 100644 (file)
--- a/fs/ext4/fsmap.c
+++ b/fs/ext4/fsmap.c
@@ -280,7 +280,7 @@ static int ext4_getfsmap_logdev(struct super_block *sb, struct ext4_fsmap *keys,
 
        /* Fabricate an rmap entry for the external log device. */
        irec.fmr_physical = journal->j_blk_offset;
-       irec.fmr_length = journal->j_maxlen;
+       irec.fmr_length = journal->j_total_len;
        irec.fmr_owner = EXT4_FMR_OWN_LOG;
        irec.fmr_flags = 0;
 

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 738a6dd..8a6dd43 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3976,7 +3976,7 @@ int ext4_calculate_overhead(struct super_block *sb)
         * loaded or not
         */
        if (sbi->s_journal && !sbi->s_journal_bdev)
-               overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_maxlen);
+               overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_total_len);
        else if (ext4_has_feature_journal(sb) && !sbi->s_journal && j_inum) {
                /* j_inum for internal journal is non-zero */
                j_inode = ext4_get_journal_inode(sb, j_inum);

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index fa688e1..ec51649 100644 (file)
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -801,7 +801,7 @@ start_journal_io:
                if (first_block < journal->j_tail)
                        freed += journal->j_last - journal->j_first;
                /* Update tail only if we free significant amount of space */
-               if (freed < journal->j_maxlen / 4)
+               if (freed < jbd2_journal_get_max_txn_bufs(journal))
                        update_tail = 0;
        }
        J_ASSERT(commit_transaction->t_state == T_COMMIT);

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 0c7c42b..c3c7682 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1348,7 +1348,7 @@ static journal_t *journal_init_common(struct block_device *bdev,
        journal->j_dev = bdev;
        journal->j_fs_dev = fs_dev;
        journal->j_blk_offset = start;
-       journal->j_maxlen = len;
+       journal->j_total_len = len;
        /* We need enough buffers to write out full descriptor block. */
        n = journal->j_blocksize / jbd2_min_tag_size();
        journal->j_wbufsize = n;
@@ -1531,7 +1531,7 @@ static int journal_reset(journal_t *journal)
        journal->j_commit_sequence = journal->j_transaction_sequence - 1;
        journal->j_commit_request = journal->j_commit_sequence;
 
-       journal->j_max_transaction_buffers = journal->j_maxlen / 4;
+       journal->j_max_transaction_buffers = jbd2_journal_get_max_txn_bufs(journal);
 
        /*
         * As a special case, if the on-disk copy is already marked as needing
@@ -1792,15 +1792,15 @@ static int journal_get_superblock(journal_t *journal)
                goto out;
        }
 
-       if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
-               journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
-       else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
+       if (be32_to_cpu(sb->s_maxlen) < journal->j_total_len)
+               journal->j_total_len = be32_to_cpu(sb->s_maxlen);
+       else if (be32_to_cpu(sb->s_maxlen) > journal->j_total_len) {
                printk(KERN_WARNING "JBD2: journal file too short\n");
                goto out;
        }
 
        if (be32_to_cpu(sb->s_first) == 0 ||
-           be32_to_cpu(sb->s_first) >= journal->j_maxlen) {
+           be32_to_cpu(sb->s_first) >= journal->j_total_len) {
                printk(KERN_WARNING
                        "JBD2: Invalid start block of journal: %u\n",
                        be32_to_cpu(sb->s_first));

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index eb26061..dc0694f 100644 (file)
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -74,8 +74,8 @@ static int do_readahead(journal_t *journal, unsigned int start)
 
        /* Do up to 128K of readahead */
        max = start + (128 * 1024 / journal->j_blocksize);
-       if (max > journal->j_maxlen)
-               max = journal->j_maxlen;
+       if (max > journal->j_total_len)
+               max = journal->j_total_len;
 
        /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
         * a time to the block device IO layer. */
@@ -134,7 +134,7 @@ static int jread(struct buffer_head **bhp, journal_t *journal,
 
        *bhp = NULL;
 
-       if (offset >= journal->j_maxlen) {
+       if (offset >= journal->j_total_len) {
                printk(KERN_ERR "JBD2: corrupted journal superblock\n");
                return -EFSCORRUPTED;
        }

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index b9a9d69..db52e84 100644 (file)
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -877,7 +877,7 @@ int ocfs2_journal_init(struct ocfs2_journal *journal, int *dirty)
                goto done;
        }
 
-       trace_ocfs2_journal_init_maxlen(j_journal->j_maxlen);
+       trace_ocfs2_journal_init_maxlen(j_journal->j_total_len);
 
        *dirty = (le32_to_cpu(di->id1.journal1.ij_flags) &
                  OCFS2_JOURNAL_DIRTY_FL);

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 1d5566a..e0b6b53 100644 (file)
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -988,9 +988,9 @@ struct journal_s
        struct block_device     *j_fs_dev;
 
        /**
-        * @j_maxlen: Total maximum capacity of the journal region on disk.
+        * @j_total_len: Total maximum capacity of the journal region on disk.
         */
-       unsigned int            j_maxlen;
+       unsigned int            j_total_len;
 
        /**
         * @j_reserved_credits:
@@ -1624,6 +1624,11 @@ int jbd2_wait_inode_data(journal_t *journal, struct jbd2_inode *jinode);
 int jbd2_fc_wait_bufs(journal_t *journal, int num_blks);
 int jbd2_fc_release_bufs(journal_t *journal);
 
+static inline int jbd2_journal_get_max_txn_bufs(journal_t *journal)
+{
+       return (journal->j_total_len - journal->j_fc_wbufsize) / 4;
+}
+
 /*
  * is_journal_abort
  *