[PATCH 5.4 29/94] ext4: using nofail preallocation in ext4_es_insert_extent()

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5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Baokun Li <libaokun1@xxxxxxxxxx>

[ Upstream commit 2a69c450083db164596c75c0f5b4d9c4c0e18eba ]

Similar to in ext4_es_insert_delayed_block(), we use preallocations that
do not fail to avoid inconsistencies, but we do not care about es that are
not must be kept, and we return 0 even if such es memory allocation fails.

Suggested-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20230424033846.4732-9-libaokun1@xxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/ext4/extents_status.c | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index fea538a66a16e..c4922b8c9d333 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -832,8 +832,11 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 {
 	struct extent_status newes;
 	ext4_lblk_t end = lblk + len - 1;
-	int err = 0;
+	int err1 = 0;
+	int err2 = 0;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct extent_status *es1 = NULL;
+	struct extent_status *es2 = NULL;
 
 	es_debug("add [%u/%u) %llu %x to extent status tree of inode %lu\n",
 		 lblk, len, pblk, status, inode->i_ino);
@@ -858,29 +861,40 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
 
 	ext4_es_insert_extent_check(inode, &newes);
 
+retry:
+	if (err1 && !es1)
+		es1 = __es_alloc_extent(true);
+	if ((err1 || err2) && !es2)
+		es2 = __es_alloc_extent(true);
 	write_lock(&EXT4_I(inode)->i_es_lock);
-	err = __es_remove_extent(inode, lblk, end, NULL, NULL);
-	if (err != 0)
+
+	err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
+	if (err1 != 0)
+		goto error;
+
+	err2 = __es_insert_extent(inode, &newes, es2);
+	if (err2 == -ENOMEM && !ext4_es_must_keep(&newes))
+		err2 = 0;
+	if (err2 != 0)
 		goto error;
-retry:
-	err = __es_insert_extent(inode, &newes, NULL);
-	if (err == -ENOMEM && __es_shrink(EXT4_SB(inode->i_sb),
-					  128, EXT4_I(inode)))
-		goto retry;
-	if (err == -ENOMEM && !ext4_es_must_keep(&newes))
-		err = 0;
 
 	if (sbi->s_cluster_ratio > 1 && test_opt(inode->i_sb, DELALLOC) &&
 	    (status & EXTENT_STATUS_WRITTEN ||
 	     status & EXTENT_STATUS_UNWRITTEN))
 		__revise_pending(inode, lblk, len);
 
+	/* es is pre-allocated but not used, free it. */
+	if (es1 && !es1->es_len)
+		__es_free_extent(es1);
+	if (es2 && !es2->es_len)
+		__es_free_extent(es2);
 error:
 	write_unlock(&EXT4_I(inode)->i_es_lock);
+	if (err1 || err2)
+		goto retry;
 
 	ext4_es_print_tree(inode);
-
-	return err;
+	return 0;
 }
 
 /*
-- 
2.42.0







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