On 12/28, Chao Yu wrote:
> On 2023/12/13 6:21, Jaegeuk Kim wrote:
> > On 12/12, Chao Yu wrote:
> > > On 2023/12/12 6:11, Jaegeuk Kim wrote:
> > > > On 12/10, Chao Yu wrote:
> > > > > This patch adds i_size check during compress inode conversion in order
> > > > > to avoid .page_mkwrite races w/ conversion.
> > > >
> > > > Which race condition do you see?
> > >
> > > Something like:
> > >
> > > - f2fs_setflags_common
> > > - check S_ISREG && F2FS_HAS_BLOCKS
> > > - mkwrite
> > > - f2fs_get_block_locked
> > > : update metadata in old inode's disk
> > > layout
> >
> > Don't we need to prevent setting this for mmapped file?
>
> Oh, we have used i_sem lock to prevent such race case, however
> we missed f2fs_disable_compressed_file():
>
> - 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);
So, needing i_sem for disabling it on mmapped file? It seems i_size would not
be enough?
>
> Thanks,
>
> >
> > > - set_compress_context
> > >
> > > Thanks,
> > >
> > > >
> > > > >
> > > > > Fixes: 4c8ff7095bef ("f2fs: support data compression")
> > > > > Signed-off-by: Chao Yu <c...@kernel.org>
> > > > > ---
> > > > > fs/f2fs/f2fs.h | 8 +++++++-
> > > > > fs/f2fs/file.c | 5 ++---
> > > > > 2 files changed, 9 insertions(+), 4 deletions(-)
> > > > >
> > > > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > > > index 65294e3b0bef..c9b8a1953913 100644
> > > > > --- a/fs/f2fs/f2fs.h
> > > > > +++ b/fs/f2fs/f2fs.h
> > > > > @@ -4397,13 +4397,19 @@ 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))
> > > > > return true;
> > > > > - if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
> > > > > + if (inode_has_data(inode))
> > > > > return false;
> > > > > fi->i_flags &= ~F2FS_COMPR_FL;
> > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > > index 1a3c29a9a6a0..8af4b29c3e1a 100644
> > > > > --- a/fs/f2fs/file.c
> > > > > +++ b/fs/f2fs/file.c
> > > > > @@ -1922,8 +1922,7 @@ 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;
> > > > > }
> > > > > @@ -3996,7 +3995,7 @@ 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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