[PATCH 8/9] ext4: check env when mapping and modifying extents

[Zhang Yi <yi.zhang@huaweicloud.com>]

From: Zhang Yi <yi.zhang@huawei.com>

Add ext4_check_map_extents_env() to the places where loading extents,
mapping blocks, removing blocks, and modifying extents, excluding the
I/O writeback context. This function will verify whether the locking
mechanisms in place are adequate.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/extents.c |  6 ++++++
 fs/ext4/inode.c   | 14 +++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b5eb89ef7ae2..52bfc042bf4e 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -611,6 +611,8 @@ int ext4_ext_precache(struct inode *inode)
 	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
 		return 0;	/* not an extent-mapped inode */
 
+	ext4_check_map_extents_env(inode);
+
 	down_read(&ei->i_data_sem);
 	depth = ext_depth(inode);
 
@@ -5342,6 +5344,8 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
 	start_lblk = offset >> inode->i_blkbits;
 	end_lblk = (offset + len) >> inode->i_blkbits;
 
+	ext4_check_map_extents_env(inode);
+
 	down_write(&EXT4_I(inode)->i_data_sem);
 	ext4_discard_preallocations(inode);
 	ext4_es_remove_extent(inode, start_lblk, EXT_MAX_BLOCKS - start_lblk);
@@ -5443,6 +5447,8 @@ static int ext4_insert_range(struct file *file, loff_t offset, loff_t len)
 	start_lblk = offset >> inode->i_blkbits;
 	len_lblk = len >> inode->i_blkbits;
 
+	ext4_check_map_extents_env(inode);
+
 	down_write(&EXT4_I(inode)->i_data_sem);
 	ext4_discard_preallocations(inode);
 
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 74c7a902a41d..1211ad7fa98d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -650,11 +650,14 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 		return -EFSCORRUPTED;
 
 	/*
-	 * Do not allow caching of unrelated ranges of extents during I/O
-	 * submission.
+	 * Callers from the context of data submission are the only exceptions
+	 * for regular files that do not hold the i_rwsem or invalidate_lock.
+	 * However, caching unrelated ranges is not permitted.
 	 */
 	if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
 		WARN_ON_ONCE(!(flags & EXT4_EX_NOCACHE));
+	else
+		ext4_check_map_extents_env(inode);
 
 	/* Lookup extent status tree firstly */
 	if (!(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) &&
@@ -1799,6 +1802,8 @@ static int ext4_da_map_blocks(struct inode *inode, struct ext4_map_blocks *map)
 	ext_debug(inode, "max_blocks %u, logical block %lu\n", map->m_len,
 		  (unsigned long) map->m_lblk);
 
+	ext4_check_map_extents_env(inode);
+
 	/* Lookup extent status tree firstly */
 	if (ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
 		map->m_len = min_t(unsigned int, map->m_len,
@@ -4110,6 +4115,8 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 	if (end_lblk > start_lblk) {
 		ext4_lblk_t hole_len = end_lblk - start_lblk;
 
+		ext4_check_map_extents_env(inode);
+
 		down_write(&EXT4_I(inode)->i_data_sem);
 		ext4_discard_preallocations(inode);
 
@@ -4262,8 +4269,9 @@ int ext4_truncate(struct inode *inode)
 	if (err)
 		goto out_stop;
 
-	down_write(&EXT4_I(inode)->i_data_sem);
+	ext4_check_map_extents_env(inode);
 
+	down_write(&EXT4_I(inode)->i_data_sem);
 	ext4_discard_preallocations(inode);
 
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
-- 
2.46.1