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f2fs: fix node_cnt race between extent node destroy and writeback

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f2fs_destroy_extent_node() does not set FI_NO_EXTENT before clearing
extent nodes. When called from f2fs_drop_inode() with I_SYNC set,
concurrent kworker writeback can insert new extent nodes into the same
extent tree, racing with the destroy and triggering f2fs_bug_on() in
__destroy_extent_node(). The scenario is as follows:

drop inode                            writeback
 - iput
  - f2fs_drop_inode  // I_SYNC set
   - f2fs_destroy_extent_node
    - __destroy_extent_node
     - while (node_cnt) {
        write_lock(&et->lock)
        __free_extent_tree
        write_unlock(&et->lock)
                                       - __writeback_single_inode
                                        - f2fs_outplace_write_data
                                         - f2fs_update_read_extent_cache
                                          - __update_extent_tree_range
                                           // FI_NO_EXTENT not set,
                                           // insert new extent node
       } // node_cnt == 0, exit while
     - f2fs_bug_on(node_cnt)  // node_cnt > 0

Additionally, __update_extent_tree_range() only checks FI_NO_EXTENT for
EX_READ type, leaving EX_BLOCK_AGE updates completely unprotected.

This patch set FI_NO_EXTENT under et->lock in __destroy_extent_node(),
consistent with other callers (__update_extent_tree_range and
__drop_extent_tree) and check FI_NO_EXTENT for both EX_READ and
EX_BLOCK_AGE tree.

Fixes: 3fc5d5a182 ("f2fs: fix to shrink read extent node in batches")
Cc: stable@vger.kernel.org
Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Yongpeng Yang
2026-04-03 22:40:17 +08:00
committed by Jaegeuk Kim
parent 2a3db1e02c
commit ed78aeebef
1 changed files with 10 additions and 7 deletions
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17
fs/f2fs/extent_cache.c
View File

@@ -119,9 +119,10 @@ static bool __may_extent_tree(struct inode *inode, enum extent_type type)
if (!__init_may_extent_tree(inode, type))
return false;
if (is_inode_flag_set(inode, FI_NO_EXTENT))
return false;
if (type == EX_READ) {
if (is_inode_flag_set(inode, FI_NO_EXTENT))
return false;
if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
!f2fs_sb_has_readonly(F2FS_I_SB(inode)))
return false;
@@ -644,6 +645,8 @@ static unsigned int __destroy_extent_node(struct inode *inode,
while (atomic_read(&et->node_cnt)) {
write_lock(&et->lock);
if (!is_inode_flag_set(inode, FI_NO_EXTENT))
set_inode_flag(inode, FI_NO_EXTENT);
node_cnt += __free_extent_tree(sbi, et, nr_shrink);
write_unlock(&et->lock);
}
@@ -688,12 +691,12 @@ static void __update_extent_tree_range(struct inode *inode,
write_lock(&et->lock);
if (type == EX_READ) {
if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
write_unlock(&et->lock);
return;
}
if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
write_unlock(&et->lock);
return;
}
if (type == EX_READ) {
prev = et->largest;
dei.len = 0;