Re: [RFC v3 3/4] ext4: Add support for generic FS events

[Leon Romanovsky <leon@leon.nu>]

On Tue, Jun 16, 2015 at 4:09 PM, Beata Michalska
<b.michalska@samsung.com> wrote:
> Add support for generic FS events including threshold
> notifications, ENOSPC and remount as read-only warnings,
> along with generic internal warnings/errors.
>
> Signed-off-by: Beata Michalska <b.michalska@samsung.com>
> ---
>  fs/ext4/balloc.c  |   10 ++++++++--
>  fs/ext4/ext4.h    |    1 +
>  fs/ext4/inode.c   |    2 +-
>  fs/ext4/mballoc.c |    6 +++++-
>  fs/ext4/resize.c  |    1 +
>  fs/ext4/super.c   |   39 +++++++++++++++++++++++++++++++++++++++
>  6 files changed, 55 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index e95b27a..a48450f 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -569,6 +569,7 @@ int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
>  {
>         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
>                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
> +               fs_event_alloc_space(sbi->s_sb, EXT4_C2B(sbi, nclusters));
>                 return 0;
>         } else
>                 return -ENOSPC;
Do you need to add "fs_event_notify(sb, FS_WARN_ENOSPC);" here too?

> @@ -590,9 +591,10 @@ int ext4_should_retry_alloc(struct super_block *sb, int *retries)
>  {
>         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
>             (*retries)++ > 3 ||
> -           !EXT4_SB(sb)->s_journal)
> +           !EXT4_SB(sb)->s_journal) {
> +               fs_event_notify(sb, FS_WARN_ENOSPC);
>                 return 0;
> -
> +       }
>         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
>
>         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
> @@ -637,6 +639,10 @@ ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
>                 dquot_alloc_block_nofail(inode,
>                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
>         }
> +
> +       if (*errp == -ENOSPC)
> +               fs_event_notify(inode->i_sb, FS_WARN_ENOSPC_META);
> +
>         return ret;
>  }
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 163afe2..7d75ff9 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2542,6 +2542,7 @@ void ext4_mark_group_corrupted(struct ext4_sb_info *sbi,
>         if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
>                 percpu_counter_sub(&sbi->s_freeclusters_counter, grp->bb_free);
>         set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
> +       fs_event_alloc_space(sbi->s_sb, EXT4_C2B(sbi, grp->bb_free));
>  }
>
>  /*
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 5cb9a21..2a7af0f 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1238,7 +1238,7 @@ static void ext4_da_release_space(struct inode *inode, int to_free)
>         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
>
>         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
> -
> +       fs_event_free_space(sbi->s_sb, to_free);
>         dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
>  }
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 24a4b6d..c2df6f0 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -4511,6 +4511,9 @@ out:
>                 kmem_cache_free(ext4_ac_cachep, ac);
>         if (inquota && ar->len < inquota)
>                 dquot_free_block(ar->inode, EXT4_C2B(sbi, inquota - ar->len));
> +       if (reserv_clstrs && ar->len < reserv_clstrs)
> +               fs_event_free_space(sbi->s_sb,
> +                       EXT4_C2B(sbi, reserv_clstrs - ar->len));
>         if (!ar->len) {
>                 if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0)
>                         /* release all the reserved blocks if non delalloc */
> @@ -4848,7 +4851,7 @@ do_more:
>         if (!(flags & EXT4_FREE_BLOCKS_NO_QUOT_UPDATE))
>                 dquot_free_block(inode, EXT4_C2B(sbi, count_clusters));
>         percpu_counter_add(&sbi->s_freeclusters_counter, count_clusters);
> -
> +       fs_event_free_space(sb, EXT4_C2B(sbi, count_clusters));
>         ext4_mb_unload_buddy(&e4b);
>
>         /* We dirtied the bitmap block */
> @@ -4982,6 +4985,7 @@ int ext4_group_add_blocks(handle_t *handle, struct super_block *sb,
>         ext4_unlock_group(sb, block_group);
>         percpu_counter_add(&sbi->s_freeclusters_counter,
>                            EXT4_NUM_B2C(sbi, blocks_freed));
> +       fs_event_free_space(sb, blocks_freed);
>
>         if (sbi->s_log_groups_per_flex) {
>                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index 8a8ec62..dbf08d6 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -1378,6 +1378,7 @@ static void ext4_update_super(struct super_block *sb,
>                            EXT4_NUM_B2C(sbi, free_blocks));
>         percpu_counter_add(&sbi->s_freeinodes_counter,
>                            EXT4_INODES_PER_GROUP(sb) * flex_gd->count);
> +       fs_event_free_space(sb, free_blocks - reserved_blocks);
>
>         ext4_debug("free blocks count %llu",
>                    percpu_counter_read(&sbi->s_freeclusters_counter));
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index e061e66..108b667 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -585,6 +585,8 @@ void __ext4_abort(struct super_block *sb, const char *function,
>                 if (EXT4_SB(sb)->s_journal)
>                         jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO);
>                 save_error_info(sb, function, line);
> +               fs_event_notify(sb, FS_ERR_REMOUNT_RO);
> +
>         }
>         if (test_opt(sb, ERRORS_PANIC))
>                 panic("EXT4-fs panic from previous error\n");
> @@ -1083,6 +1085,12 @@ static const struct quotactl_ops ext4_qctl_operations = {
>  };
>  #endif
>
> +static void ext4_trace_query(struct super_block *sb, u64 *ncount);
> +
> +static const struct fs_trace_operations ext4_trace_ops = {
> +       .query  = ext4_trace_query,
> +};
> +
>  static const struct super_operations ext4_sops = {
>         .alloc_inode    = ext4_alloc_inode,
>         .destroy_inode  = ext4_destroy_inode,
> @@ -3398,11 +3406,20 @@ static int ext4_reserve_clusters(struct ext4_sb_info *sbi, ext4_fsblk_t count)
>  {
>         ext4_fsblk_t clusters = ext4_blocks_count(sbi->s_es) >>
>                                 sbi->s_cluster_bits;
> +       ext4_fsblk_t current_resv;
>
>         if (count >= clusters)
>                 return -EINVAL;
>
> +       current_resv = atomic64_read(&sbi->s_resv_clusters);
>         atomic64_set(&sbi->s_resv_clusters, count);
> +
> +       if (count > current_resv)
> +               fs_event_alloc_space(sbi->s_sb,
> +                       EXT4_C2B(sbi, count - current_resv));
> +       else
> +               fs_event_free_space(sbi->s_sb,
> +                       EXT4_C2B(sbi, current_resv - count));
>         return 0;
>  }
>
> @@ -3966,6 +3983,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>                 sb->s_qcop = &ext4_qctl_operations;
>         sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
>  #endif
> +       sb->s_etrace.ops = &ext4_trace_ops;
> +       sb->s_etrace.events_cap_mask = FS_EVENTS_ALL;
> +
>         memcpy(sb->s_uuid, es->s_uuid, sizeof(es->s_uuid));
>
>         INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */
> @@ -5438,6 +5458,25 @@ out:
>
>  #endif
>
> +static void ext4_trace_query(struct super_block *sb, u64 *ncount)
> +{
> +       struct ext4_sb_info *sbi = EXT4_SB(sb);
> +       struct ext4_super_block *es = sbi->s_es;
> +       ext4_fsblk_t rsv_blocks;
> +       ext4_fsblk_t nblocks;
> +
> +       nblocks = percpu_counter_sum_positive(&sbi->s_freeclusters_counter) -
> +               percpu_counter_sum_positive(&sbi->s_dirtyclusters_counter);
> +       nblocks = EXT4_C2B(sbi, nblocks);
> +       rsv_blocks = ext4_r_blocks_count(es) +
> +                    EXT4_C2B(sbi, atomic64_read(&sbi->s_resv_clusters));
> +       if (nblocks < rsv_blocks)
> +               nblocks = 0;
> +       else
> +               nblocks -= rsv_blocks;
> +       *ncount = nblocks;
> +}
> +
>  static struct dentry *ext4_mount(struct file_system_type *fs_type, int flags,
>                        const char *dev_name, void *data)
>  {
> --
> 1.7.9.5
>
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-- 
Leon Romanovsky | Independent Linux Consultant
        www.leon.nu | leon@leon.nu