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ext4: introduce ext4_check_map_extents_env() debug helper 

Loading and modifying the extents tree and extent status tree without
holding the inode's i_rwsem or the mapping's invalidate_lock is not
permitted, except during the I/O writeback. Add a new debug helper
ext4_check_map_extents_env(), it will verify whether the extent
loading/modifying context is safe.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250423085257.122685-8-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi 2025-04-23 16:52:55 +08:00 committed by Theodore Ts'o
parent 0b8e0bd450
commit 7871da20d4
2 changed files with 27 additions and 0 deletions
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1
fs/ext4/ext4.h
View File

@ -2978,6 +2978,7 @@ static inline bool ext4_mb_cr_expensive(enum criteria cr)
void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
struct ext4_inode_info *ei);
int ext4_inode_is_fast_symlink(struct inode *inode);
void ext4_check_map_extents_env(struct inode *inode);
struct buffer_head *ext4_getblk(handle_t *, struct inode *, ext4_lblk_t, int);
struct buffer_head *ext4_bread(handle_t *, struct inode *, ext4_lblk_t, int);
int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,

26
fs/ext4/inode.c
View File

@ -416,6 +416,32 @@ int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
return ret;
}
/*
* For generic regular files, when updating the extent tree, Ext4 should
* hold the i_rwsem and invalidate_lock exclusively. This ensures
* exclusion against concurrent page faults, as well as reads and writes.
*/
#ifdef CONFIG_EXT4_DEBUG
void ext4_check_map_extents_env(struct inode *inode)
{
if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
return;
if (!S_ISREG(inode->i_mode) ||
IS_NOQUOTA(inode) || IS_VERITY(inode) ||
is_special_ino(inode->i_sb, inode->i_ino) ||
(inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW)) ||
ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE) ||
ext4_verity_in_progress(inode))
return;
WARN_ON_ONCE(!inode_is_locked(inode) &&
!rwsem_is_locked(&inode->i_mapping->invalidate_lock));
}
#else
void ext4_check_map_extents_env(struct inode *inode) {}
#endif
#define check_block_validity(inode, map) \
__check_block_validity((inode), __func__, __LINE__, (map))