On Aug 8, 2019, at 9:45 PM, Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx> wrote:
>
> This patch adds new helper APIs that ext4 needs for fast
> commits. These new fast commit APIs are used by subsequent fast commit
> patches to implement fast commits. Following new APIs are added:
>
> /*
> * Returns when either a full commit or a fast commit
> * completes
> */
> int jbd2_fc_complete_commit(journal_tc *journal, tid_t tid,
> tid_t tid, tid_t subtid)
>
> /* Send all the data buffers related to an inode */
> int journal_submit_inode_data(journal_t *journal,
> struct jbd2_inode *jinode)
>
> /* Map one fast commit buffer for use by the file system */
> int jbd2_map_fc_buf(journal_t *journal, struct buffer_head **bh_out)
>
> /* Wait on fast commit buffers to complete IO */
> jbd2_wait_on_fc_bufs(journal_t *journal, int num_bufs)
>
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> ---
>
> Changelog:
>
> V2: 1) Fixed error reported by kbuild test robot. Removed duplicate
> EXPORT_SYMBOL() call. Also, added EXPORT_SYMBOL() for the new
> APIs introduced.
> 2) Changed jbd2_submit_fc_bufs() to jbd2_wait_on_fc_bufs(). This
> gives client file system to submit JBD2 buffers according to
> its own convenience.
> ---
> fs/jbd2/commit.c | 32 +++++++++++++++
> fs/jbd2/journal.c | 98 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/jbd2.h | 6 +++
> 3 files changed, 136 insertions(+)
>
> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> index 9281814606e7..db62a53436e3 100644
> --- a/fs/jbd2/commit.c
> +++ b/fs/jbd2/commit.c
> @@ -202,6 +202,38 @@ static int journal_submit_inode_data_buffers(struct address_space *mapping,
> return ret;
> }
>
> +int jbd2_submit_inode_data(journal_t *journal, struct jbd2_inode *jinode)
> +{
> + struct address_space *mapping;
> + loff_t dirty_start = jinode->i_dirty_start;
> + loff_t dirty_end = jinode->i_dirty_end;
> + int ret;
> +
> + if (!jinode)
> + return 0;
> +
> + if (!(jinode->i_flags & JI_WRITE_DATA))
> + return 0;
> +
> + dirty_start = jinode->i_dirty_start;
> + dirty_end = jinode->i_dirty_end;
> +
> + mapping = jinode->i_vfs_inode->i_mapping;
> + jinode->i_flags |= JI_COMMIT_RUNNING;
> +
> + trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
> + ret = journal_submit_inode_data_buffers(mapping, dirty_start,
> + dirty_end);
> +
> + jinode->i_flags &= ~JI_COMMIT_RUNNING;
> + /* Protect JI_COMMIT_RUNNING flag */
> + smp_mb();
> + wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(jbd2_submit_inode_data);
> +
> /*
> * Submit all the data buffers of inode associated with the transaction to
> * disk.
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index ab05e47ed2d4..1e15804b2c3c 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -811,6 +811,33 @@ int jbd2_complete_transaction(journal_t *journal, tid_t tid)
> }
> EXPORT_SYMBOL(jbd2_complete_transaction);
>
> +int jbd2_fc_complete_commit(journal_t *journal, tid_t tid, tid_t subtid)
> +{
> + int need_to_wait = 1;
> +
> + read_lock(&journal->j_state_lock);
> + if (journal->j_running_transaction &&
> + journal->j_running_transaction->t_tid == tid) {
> + /* Check if fast commit was already done */
> + if (journal->j_subtid > subtid)
> + need_to_wait = 0;
> + if (journal->j_commit_request != tid) {
> + /* transaction not yet started, so request it */
> + read_unlock(&journal->j_state_lock);
> + jbd2_log_start_commit(journal, tid, false);
> + goto wait_commit;
> + }
> + } else if (!(journal->j_committing_transaction &&
> + journal->j_committing_transaction->t_tid == tid))
> + need_to_wait = 0;
> + read_unlock(&journal->j_state_lock);
> + if (!need_to_wait)
> + return 0;
> +wait_commit:
> + return __jbd2_log_wait_commit(journal, tid, subtid);
> +}
> +EXPORT_SYMBOL(jbd2_fc_complete_commit);
> +
> /*
> * Log buffer allocation routines:
> */
> @@ -831,6 +858,77 @@ int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
> return jbd2_journal_bmap(journal, blocknr, retp);
> }
>
> +int jbd2_map_fc_buf(journal_t *journal, struct buffer_head **bh_out)
> +{
> + unsigned long long pblock;
> + unsigned long blocknr;
> + int ret = 0;
> + struct buffer_head *bh;
> + int fc_off;
> + journal_header_t *jhdr;
> +
> + write_lock(&journal->j_state_lock);
> +
> + if (journal->j_fc_off + journal->j_first_fc < journal->j_last_fc) {
> + fc_off = journal->j_fc_off;
> + blocknr = journal->j_first_fc + fc_off;
> + journal->j_fc_off++;
> + } else {
> + ret = -EINVAL;
> + }
> + write_unlock(&journal->j_state_lock);
> +
> + if (ret)
> + return ret;
> +
> + ret = jbd2_journal_bmap(journal, blocknr, &pblock);
> + if (ret)
> + return ret;
> +
> + bh = __getblk(journal->j_dev, pblock, journal->j_blocksize);
> + if (!bh)
> + return -ENOMEM;
> +
> + lock_buffer(bh);
> + jhdr = (journal_header_t *)bh->b_data;
> + jhdr->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
> + jhdr->h_blocktype = cpu_to_be32(JBD2_FC_BLOCK);
> + jhdr->h_sequence = cpu_to_be32(journal->j_running_transaction->t_tid);
> +
> + set_buffer_uptodate(bh);
> + unlock_buffer(bh);
> + journal->j_fc_wbuf[fc_off] = bh;
> +
> + *bh_out = bh;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(jbd2_map_fc_buf);
> +
> +int jbd2_wait_on_fc_bufs(journal_t *journal, int num_blks)
> +{
> + struct buffer_head *bh;
> + int i, j_fc_off;
> +
> + read_lock(&journal->j_state_lock);
> + j_fc_off = journal->j_fc_off;
> + read_unlock(&journal->j_state_lock);
> +
> + /*
> + * Wait in reverse order to minimize chances of us being woken up before
> + * all IOs have completed
> + */
> + for (i = j_fc_off - 1; i >= j_fc_off - num_blks; i--) {
> + bh = journal->j_fc_wbuf[i];
> + wait_on_buffer(bh);
> + if (unlikely(!buffer_uptodate(bh)))
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(jbd2_wait_on_fc_bufs);
> +
> /*
> * Conversion of logical to physical block numbers for the journal
> *
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 535f88dff653..5362777d06f8 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -124,6 +124,7 @@ typedef struct journal_s journal_t; /* Journal control structure */
> #define JBD2_SUPERBLOCK_V1 3
> #define JBD2_SUPERBLOCK_V2 4
> #define JBD2_REVOKE_BLOCK 5
> +#define JBD2_FC_BLOCK 6
>
> /*
> * Standard header for all descriptor blocks:
> @@ -1582,6 +1583,7 @@ int jbd2_transaction_committed(journal_t *journal, tid_t tid);
> int jbd2_complete_transaction(journal_t *journal, tid_t tid);
> int jbd2_log_do_checkpoint(journal_t *journal);
> int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
> +int jbd2_fc_complete_commit(journal_t *journal, tid_t tid, tid_t subtid);
>
> void __jbd2_log_wait_for_space(journal_t *journal);
> extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
> @@ -1732,6 +1734,10 @@ static inline tid_t jbd2_get_latest_transaction(journal_t *journal)
> return tid;
> }
>
> +int jbd2_map_fc_buf(journal_t *journal, struct buffer_head **bh_out);
> +int jbd2_wait_on_fc_bufs(journal_t *journal, int num_blks);
> +int jbd2_submit_inode_data(journal_t *journal, struct jbd2_inode *jinode);
> +
> #ifdef __KERNEL__
>
> #define buffer_trace_init(bh) do {} while (0)
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>
Cheers, Andreas
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