[PATCH v7 05/12] ext4: call ext4_mb_mark_context in ext4_mb_mark_diskspace_used

Kemeng Shi posted 12 patches 5 months, 1 week ago
There is a newer version of this series
[PATCH v7 05/12] ext4: call ext4_mb_mark_context in ext4_mb_mark_diskspace_used
Posted by Kemeng Shi 5 months, 1 week ago
call ext4_mb_mark_context in ext4_mb_mark_diskspace_used to:
1. remove repeat code to normally update bitmap and group descriptor
on disk.
2. call ext4_mb_mark_context instead of only setting bits in block bitmap
to fix the bitmap. Function ext4_mb_mark_context will also update
checksum of bitmap and other counter along with the bit change to keep
the cosistent with bit change or block bitmap will be marked corrupted as
checksum of bitmap is in inconsistent state.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
---
 fs/ext4/mballoc.c | 86 +++++++++++------------------------------------
 1 file changed, 20 insertions(+), 66 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index bdf07b2904ca..87e5922997fb 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4063,13 +4063,13 @@ static noinline_for_stack int
 ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 				handle_t *handle, unsigned int reserv_clstrs)
 {
-	struct buffer_head *bitmap_bh = NULL;
 	struct ext4_group_desc *gdp;
-	struct buffer_head *gdp_bh;
 	struct ext4_sb_info *sbi;
 	struct super_block *sb;
 	ext4_fsblk_t block;
 	int err, len;
+	int flags = 0;
+	ext4_grpblk_t changed;
 
 	BUG_ON(ac->ac_status != AC_STATUS_FOUND);
 	BUG_ON(ac->ac_b_ex.fe_len <= 0);
@@ -4077,32 +4077,13 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 	sb = ac->ac_sb;
 	sbi = EXT4_SB(sb);
 
-	bitmap_bh = ext4_read_block_bitmap(sb, ac->ac_b_ex.fe_group);
-	if (IS_ERR(bitmap_bh)) {
-		return PTR_ERR(bitmap_bh);
-	}
-
-	BUFFER_TRACE(bitmap_bh, "getting write access");
-	err = ext4_journal_get_write_access(handle, sb, bitmap_bh,
-					    EXT4_JTR_NONE);
-	if (err)
-		goto out_err;
-
-	err = -EIO;
-	gdp = ext4_get_group_desc(sb, ac->ac_b_ex.fe_group, &gdp_bh);
+	gdp = ext4_get_group_desc(sb, ac->ac_b_ex.fe_group, NULL);
 	if (!gdp)
-		goto out_err;
-
+		return -EIO;
 	ext4_debug("using block group %u(%d)\n", ac->ac_b_ex.fe_group,
 			ext4_free_group_clusters(sb, gdp));
 
-	BUFFER_TRACE(gdp_bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, sb, gdp_bh, EXT4_JTR_NONE);
-	if (err)
-		goto out_err;
-
 	block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
-
 	len = EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
 	if (!ext4_inode_block_valid(ac->ac_inode, block, len)) {
 		ext4_error(sb, "Allocating blocks %llu-%llu which overlap "
@@ -4111,41 +4092,29 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 		 * Fix the bitmap and return EFSCORRUPTED
 		 * We leak some of the blocks here.
 		 */
-		ext4_lock_group(sb, ac->ac_b_ex.fe_group);
-		mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
-			      ac->ac_b_ex.fe_len);
-		ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
-		err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
+		err = ext4_mb_mark_context(handle, sb, true,
+					   ac->ac_b_ex.fe_group,
+					   ac->ac_b_ex.fe_start,
+					   ac->ac_b_ex.fe_len,
+					   0, NULL);
 		if (!err)
 			err = -EFSCORRUPTED;
-		goto out_err;
+		return err;
 	}
 
-	ext4_lock_group(sb, ac->ac_b_ex.fe_group);
 #ifdef AGGRESSIVE_CHECK
-	{
-		int i;
-		for (i = 0; i < ac->ac_b_ex.fe_len; i++) {
-			BUG_ON(mb_test_bit(ac->ac_b_ex.fe_start + i,
-						bitmap_bh->b_data));
-		}
-	}
+	flags |= EXT4_MB_BITMAP_MARKED_CHECK;
 #endif
-	mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
-		      ac->ac_b_ex.fe_len);
-	if (ext4_has_group_desc_csum(sb) &&
-	    (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
-		gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
-		ext4_free_group_clusters_set(sb, gdp,
-					     ext4_free_clusters_after_init(sb,
-						ac->ac_b_ex.fe_group, gdp));
-	}
-	len = ext4_free_group_clusters(sb, gdp) - ac->ac_b_ex.fe_len;
-	ext4_free_group_clusters_set(sb, gdp, len);
-	ext4_block_bitmap_csum_set(sb, gdp, bitmap_bh);
-	ext4_group_desc_csum_set(sb, ac->ac_b_ex.fe_group, gdp);
+	err = ext4_mb_mark_context(handle, sb, true, ac->ac_b_ex.fe_group,
+				   ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len,
+				   flags, &changed);
+
+	if (err && changed == 0)
+		return err;
 
-	ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
+#ifdef AGGRESSIVE_CHECK
+	BUG_ON(changed != ac->ac_b_ex.fe_len);
+#endif
 	percpu_counter_sub(&sbi->s_freeclusters_counter, ac->ac_b_ex.fe_len);
 	/*
 	 * Now reduce the dirty block count also. Should not go negative
@@ -4155,21 +4124,6 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
 		percpu_counter_sub(&sbi->s_dirtyclusters_counter,
 				   reserv_clstrs);
 
-	if (sbi->s_log_groups_per_flex) {
-		ext4_group_t flex_group = ext4_flex_group(sbi,
-							  ac->ac_b_ex.fe_group);
-		atomic64_sub(ac->ac_b_ex.fe_len,
-			     &sbi_array_rcu_deref(sbi, s_flex_groups,
-						  flex_group)->free_clusters);
-	}
-
-	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
-	if (err)
-		goto out_err;
-	err = ext4_handle_dirty_metadata(handle, NULL, gdp_bh);
-
-out_err:
-	brelse(bitmap_bh);
 	return err;
 }
 
-- 
2.30.0
Re: [PATCH v7 05/12] ext4: call ext4_mb_mark_context in ext4_mb_mark_diskspace_used
Posted by Ritesh Harjani (IBM) 5 months ago
Kemeng Shi <shikemeng@huaweicloud.com> writes:

> call ext4_mb_mark_context in ext4_mb_mark_diskspace_used to:
> 1. remove repeat code to normally update bitmap and group descriptor
> on disk.
> 2. call ext4_mb_mark_context instead of only setting bits in block bitmap
> to fix the bitmap. Function ext4_mb_mark_context will also update
> checksum of bitmap and other counter along with the bit change to keep
> the cosistent with bit change or block bitmap will be marked corrupted as
> checksum of bitmap is in inconsistent state.
>

Rewording point 2 to... 
Now that we have a common API for marking blocks inuse/free in block
bitmap, use that instead of open coding it in function
ext4_mb_mark_diskspace_used(). The current code was not updating
checksum and other counters. ext4_mb_mark_context() should fix these
consistency problems.


Also I now see why you have used "int" (ext4_grpblk_t) for len in
ext4_mb_mark_context(). The reason is because this is "cluster len" which
is defined as ext4_grpblk_t in "struct ext4_free_extent"

I think by default we anyway have 8192 blocks per block group. So it
should be ok for now. I anyway think the usage of blocks and cluster (&
their data type) is confusing at different places which needs an auditing/cleanup.

This patch looks good to me. Feel free to add - 

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>