> On 9/10/25 21:58, wangzijie wrote:
> > When the data layout is like this:
> > dnode1: dnode2:
> > [0] A [0] NEW_ADDR
> > [1] A+1 [1] 0x0
> > ... ....
> > [1016] A+1016
> > [1017] B (B!=A+1017) [1017] 0x0
> >
> > We can build this kind of layout by following steps(with i_extra_isize:36):
> > ./f2fs_io write 1 0 1881 rand dsync testfile
> > ./f2fs_io write 1 1881 1 rand buffered testfile
> > ./f2fs_io fallocate 0 7708672 4096 testfile
> >
> > And when we map first data block in dnode2, we will get wrong extent_info
> > data:
> > map->m_len = 1
> > ofs = start_pgofs - map->m_lblk = 1882 - 1881 = 1
> >
> > ei.fofs = start_pgofs = 1882
> > ei.len = map->m_len - ofs = 1 - 1 = 0
> >
> > Fix it by skipping updating this kind of extent info.
> >
> > Signed-off-by: wangzijie <wangzij...@honor.com>
> > ---
> > fs/f2fs/data.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 7961e0ddf..b8bb71852 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -1649,6 +1649,9 @@ int f2fs_map_blocks(struct inode *inode, struct
> > f2fs_map_blocks *map, int flag)
> >
> > switch (flag) {
> > case F2FS_GET_BLOCK_PRECACHE:
> > + if (__is_valid_data_blkaddr(map->m_pblk) &&
> > + start_pgofs - map->m_lblk == map->m_len)
> > + map->m_flags &= ~F2FS_MAP_MAPPED;
>
> It looks we missed to reset value for map variable in f2fs_precache_extents(),
> what do you think of this?
>
> ---
> fs/f2fs/file.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 1aae4361d0a8..2b14151d4130 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3599,7 +3599,7 @@ static int f2fs_ioc_io_prio(struct file *filp, unsigned
> long arg)
> int f2fs_precache_extents(struct inode *inode)
> {
> struct f2fs_inode_info *fi = F2FS_I(inode);
> - struct f2fs_map_blocks map;
> + struct f2fs_map_blocks map = { 0 };
> pgoff_t m_next_extent;
> loff_t end;
> int err;
> @@ -3617,6 +3617,8 @@ int f2fs_precache_extents(struct inode *inode)
>
> while (map.m_lblk < end) {
> map.m_len = end - map.m_lblk;
> + map.m_pblk = 0;
> + map.m_flags = 0;
>
> f2fs_down_write(&fi->i_gc_rwsem[WRITE]);
> err = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_PRECACHE);
> --
> 2.49.0
>
> Thanks,
>
> > goto sync_out;
> > case F2FS_GET_BLOCK_BMAP:
> > map->m_pblk = 0;
We have already reset m_flags (map->m_flags = 0) in f2fs_map_blocks().
I think that this bug is caused by we missed to reset m_flags when we
goto next_dnode in below caseļ¼
Data layout is something like this:
dnode1: dnode2:
[0] A [0] NEW_ADDR
[1] A+1 [1] 0x0
...
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
we map the last block(valid blkaddr) in dnode1:
map->m_flags |= F2FS_MAP_MAPPED;
map->m_pblk = blkaddr(valid blkaddr);
map->m_len = 1;
then we goto next_dnode, meet the first block in dnode2(hole), goto sync_out:
map->m_flags & F2FS_MAP_MAPPED == true, and we make wrong blkaddr/len for
extent_info.
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