On 2023/3/31 17:26, Bo Ye wrote:
From: Qilin Tan <qilin....@mediatek.com>

Need add __pack for struct extent_info to align to memory
layout of struct rb_entry.

Jaegeuk has fixed this bug w/ below patchset, please check it:

https://lore.kernel.org/linux-f2fs-devel/20230313201216.924234-1-jaeg...@kernel.org/

Thanks,


struct rb_entry {
     struct rb_node rb_node;     /* rb node located in rb-tree */
     union {
         struct {
             unsigned int ofs;   /* start offset of the entry */
             unsigned int len;   /* length of the entry */
         };
         unsigned long long key;     /* 64-bits key */
     } __packed;
};

struct extent_info {
     unsigned int fofs;      /* start offset in a file */
     unsigned int len;       /* length of the extent */
     union {
         ...
         /* block age extent_cache */
         struct {
             /* block age of the extent */
             unsigned long long age;
             /* last total blocks allocated */
             unsigned long long last_blocks;
         };
};

The new fields(age, last_blocks) are u64 in change 71644dff4811, it
cause the memory alignment based on 8 bytes in some complier. So the
field fofs and len are alloced with 8 bytes and using the last 4 byts.
Its memory is not aligned with struct rb_entry. the ofs of rb_entry
pointer to a invalid value and cause writing file failed.

struct extent_info's offset should be 12 rather than 16 from the
beginning of struct rb_entry.

The offset dump for the bad case as:
kworker/u16:6: [name:f2fs&]f2fs_lookup_rb_tree_for_insert:MTK_DEBUG: ino=1629 
re=0xc675dc08 ofs=0 re->ofs=0, re->len=68 ei=0xc675dc18 ei.fofs=68 ei.len=277

Fixes: 71644dff4811 ("f2fs: add block_age-based extent cache")
Signed-off-by: Bo Ye <bo...@mediatek.com>
Signed-off-by: Qilin Tan <qilin....@mediatek.com>
---
  fs/f2fs/f2fs.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index b0ab2062038a..7c690667a42f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -660,7 +660,7 @@ struct extent_info {
                        unsigned long long last_blocks;
                };
        };
-};
+} __packed;
struct extent_node {
        struct rb_node rb_node;         /* rb node located in rb-tree */


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