[PATCH] ext4: fix possible memory leak when enable bigalloc feature

[Ye Bin]

From: Ye Bin <yebin10@xxxxxxxxxx>

Syzbot found the following issue:
BUG: memory leak
unreferenced object 0xffff8881bde17420 (size 32):
  comm "rep", pid 2327, jiffies 4295381963 (age 32.265s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000ac6d38f8>] __insert_pending+0x13c/0x2d0
    [<00000000d717de3b>] ext4_es_insert_delayed_block+0x399/0x4e0
    [<000000004be03913>] ext4_da_map_blocks.constprop.0+0x739/0xfa0
    [<00000000885a832a>] ext4_da_get_block_prep+0x10c/0x440
    [<0000000029b7f8ef>] __block_write_begin_int+0x28d/0x860
    [<00000000e182ebc3>] ext4_da_write_inline_data_begin+0x2d1/0xf30
    [<00000000ced0c8a2>] ext4_da_write_begin+0x612/0x860
    [<000000008d5f27fa>] generic_perform_write+0x215/0x4d0
    [<00000000552c1cde>] ext4_buffered_write_iter+0x101/0x3b0
    [<0000000052177ae8>] do_iter_readv_writev+0x19f/0x340
    [<000000004b9de834>] do_iter_write+0x13b/0x650
    [<00000000e2401b9b>] iter_file_splice_write+0x5a5/0xab0
    [<0000000023aa5d90>] direct_splice_actor+0x103/0x1e0
    [<0000000089e00fc1>] splice_direct_to_actor+0x2c9/0x7b0
    [<000000004386851e>] do_splice_direct+0x159/0x280
    [<00000000b567e609>] do_sendfile+0x932/0x1200

Now, 'ext4_clear_inode' don't cleanup pending tree which will lead to memory
leak.
To solve above issue, cleanup pending tree when clear inode.

Reported-by: syzbot+05a0f0ccab4a25626e38@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
---
 fs/ext4/extents_status.c | 22 ++++++++++++++++++++++
 fs/ext4/extents_status.h |  1 +
 fs/ext4/super.c          |  1 +
 3 files changed, 24 insertions(+)

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index cd0a861853e3..5f6b218464de 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1947,6 +1947,28 @@ void ext4_remove_pending(struct inode *inode, ext4_lblk_t lblk)
 	write_unlock(&ei->i_es_lock);
 }
 
+void ext4_clear_inode_pending(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct pending_reservation *pr;
+	struct ext4_pending_tree *tree;
+	struct rb_node *node;
+
+	if (EXT4_SB(inode->i_sb)->s_cluster_ratio == 1)
+		return;
+
+	write_lock(&ei->i_es_lock);
+	tree = &EXT4_I(inode)->i_pending_tree;
+	node = rb_first(&tree->root);
+	while (node) {
+		pr = rb_entry(node, struct pending_reservation, rb_node);
+		node = rb_next(node);
+		rb_erase(&pr->rb_node, &tree->root);
+		kmem_cache_free(ext4_pending_cachep, pr);
+	}
+	write_unlock(&ei->i_es_lock);
+}
+
 /*
  * ext4_is_pending - determine whether a cluster has a pending reservation
  *                   on it
diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
index 4ec30a798260..25b605309c06 100644
--- a/fs/ext4/extents_status.h
+++ b/fs/ext4/extents_status.h
@@ -248,6 +248,7 @@ extern int __init ext4_init_pending(void);
 extern void ext4_exit_pending(void);
 extern void ext4_init_pending_tree(struct ext4_pending_tree *tree);
 extern void ext4_remove_pending(struct inode *inode, ext4_lblk_t lblk);
+extern void ext4_clear_inode_pending(struct inode *inode);
 extern bool ext4_is_pending(struct inode *inode, ext4_lblk_t lblk);
 extern int ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
 					bool allocated);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 106fb06e24e8..160667dcf09a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1434,6 +1434,7 @@ void ext4_clear_inode(struct inode *inode)
 	clear_inode(inode);
 	ext4_discard_preallocations(inode, 0);
 	ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS);
+	ext4_clear_inode_pending(inode);
 	dquot_drop(inode);
 	if (EXT4_I(inode)->jinode) {
 		jbd2_journal_release_jbd_inode(EXT4_JOURNAL(inode),
-- 
2.31.1