The following race could lead to inconsistent SIT bitmap:
Task A Task B
====== ======
f2fs_write_checkpoint
block_operations
f2fs_lock_all
down_write(node_change)
down_write(node_write)
... sync ...
up_write(node_change)
f2fs_file_write_iter
set_inode_flag(FI_NO_PREALLOC)
......
f2fs_write_begin(index=0, has inline data)
prepare_write_begin
__do_map_lock(AIO) =>
down_read(node_change)
f2fs_convert_inline_page => update SIT
__do_map_lock(AIO) => up_read(node_change)
f2fs_flush_sit_entries <= inconsistent SIT
finish write checkpoint
sudden-power-off
If SPO occurs after checkpoint is finished, SIT bitmap will be set
incorrectly.
Signed-off-by: Sheng Yong <[email protected]>
---
v2->v1:
Sorry for late. We can use f2fs_lock_op directly, but it makes it a bit
complicate to unlock. So v2 still uses __do_map_lock with different flags
to avoid race.
Use F2FS_GET_BLOCK_PRE_AIO and F2FS_GET_BLOCK_DEFAULT to tell different
condition.
Thanks
---
fs/f2fs/data.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6e0ffb1749ca..4abd47d82cdb 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2376,6 +2376,7 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
struct page *ipage;
bool locked = false;
struct extent_info ei = {0,0,0};
+ int flag = F2FS_GET_BLOCK_PRE_AIO;
int err = 0;
/*
@@ -2386,9 +2387,12 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
!is_inode_flag_set(inode, FI_NO_PREALLOC))
return 0;
+ if (f2fs_has_inline_data(inode) && pos + len > MAX_INLINE_DATA(inode))
+ /* avoid race between write CP and convert_inline_page */
+ flag = F2FS_GET_BLOCK_DEFAULT;
if (f2fs_has_inline_data(inode) ||
(pos & PAGE_MASK) >= i_size_read(inode)) {
- __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true);
+ __do_map_lock(sbi, flag, true);
locked = true;
}
restart:
@@ -2424,8 +2428,8 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
err = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
if (err || dn.data_blkaddr == NULL_ADDR) {
f2fs_put_dnode(&dn);
- __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO,
- true);
+ flag = F2FS_GET_BLOCK_PRE_AIO;
+ __do_map_lock(sbi, flag, true);
locked = true;
goto restart;
}
@@ -2439,7 +2443,7 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
f2fs_put_dnode(&dn);
unlock_out:
if (locked)
- __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, false);
+ __do_map_lock(sbi, flag, false);
return err;
}
--
2.17.1
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