Re: [f2fs-dev] [PATCH] f2fs: compress: fix to cover f2fs_disable_compressed_file() w/ i_sem

[Chao Yu]

On 2024/1/17 2:29, Jaegeuk Kim wrote:

On 01/11, Chao Yu wrote:

- f2fs_disable_compressed_file
   - check inode_has_data
                                        - f2fs_file_mmap
                                        - mkwrite
                                         - f2fs_get_block_locked
                                         : update metadata in compressed
                                           inode's disk layout
   - fi->i_flags &= ~F2FS_COMPR_FL
   - clear_inode_flag(inode, FI_COMPRESSED_FILE);

we should use i_sem lock to prevent above race case.

Meanwhile, this patch adds i_size check to restrict compress inode
conversion condition.

Sorry, what was the reason to check i_size?

Oh, I don't see any race condition, let's remove it in v2.

Thanks,

Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Chao Yu <c...@kernel.org>
---
  fs/f2fs/f2fs.h | 18 ++++++++++++++++--
  fs/f2fs/file.c |  5 ++---
  2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 74729db0b381..e2e0ca45f881 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -4406,19 +4406,33 @@ static inline int set_compress_context(struct inode 
*inode)
  #endif
  }

+static inline bool inode_has_data(struct inode *inode)

+{
+       return (S_ISREG(inode->i_mode) &&
+               (F2FS_HAS_BLOCKS(inode) || i_size_read(inode)));
+}
+
  static inline bool f2fs_disable_compressed_file(struct inode *inode)
  {
        struct f2fs_inode_info *fi = F2FS_I(inode);

- if (!f2fs_compressed_file(inode))

+       f2fs_down_write(&F2FS_I(inode)->i_sem);
+
+       if (!f2fs_compressed_file(inode)) {
+               f2fs_up_write(&F2FS_I(inode)->i_sem);
                return true;
-       if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
+       }
+       if (f2fs_is_mmap_file(inode) || inode_has_data(inode)) {
+               f2fs_up_write(&F2FS_I(inode)->i_sem);
                return false;
+       }

fi->i_flags &= ~F2FS_COMPR_FL;

        stat_dec_compr_inode(inode);
        clear_inode_flag(inode, FI_COMPRESSED_FILE);
        f2fs_mark_inode_dirty_sync(inode, true);
+
+       f2fs_up_write(&F2FS_I(inode)->i_sem);
        return true;
  }

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c

index 0e4c871d6aed..5e5df234eb92 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1926,8 +1926,7 @@ static int f2fs_setflags_common(struct inode *inode, u32 
iflags, u32 mask)

f2fs_down_write(&F2FS_I(inode)->i_sem);

                        if (!f2fs_may_compress(inode) ||
-                                       (S_ISREG(inode->i_mode) &&
-                                       F2FS_HAS_BLOCKS(inode))) {
+                                       inode_has_data(inode)) {
                                f2fs_up_write(&F2FS_I(inode)->i_sem);
                                return -EINVAL;
                        }
@@ -4011,7 +4010,7 @@ static int f2fs_ioc_set_compress_option(struct file 
*filp, unsigned long arg)
                goto out;
        }

- if (F2FS_HAS_BLOCKS(inode)) {

+       if (inode_has_data(inode)) {
                ret = -EFBIG;
                goto out;
        }
--
2.40.1

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