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f2fs: fix to avoid mmap vs set_compress_option case 

Compression option in inode should not be changed after they have
been used, however, it may happen in below race case:

Thread A				Thread B
- f2fs_ioc_set_compress_option
 - check f2fs_is_mmap_file()
 - check get_dirty_pages()
 - check F2FS_HAS_BLOCKS()
					- f2fs_file_mmap
					 - set_inode_flag(FI_MMAP_FILE)
					- fault
					 - do_page_mkwrite
					  - f2fs_vm_page_mkwrite
					  - f2fs_get_block_locked
					 - fault_dirty_shared_page
					  - set_page_dirty
 - update i_compress_algorithm
 - update i_log_cluster_size
 - update i_cluster_size

Avoid such race condition by covering f2fs_file_mmap() w/ i_sem lock,
meanwhile add mmap file check condition in f2fs_may_compress() as well.

Fixes: e1e8debec6 ("f2fs: add F2FS_IOC_SET_COMPRESS_OPTION ioctl")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2023-07-06 10:06:14 +08:00 committed by Jaegeuk Kim
parent c709d099a0
commit b5ab3276eb
2 changed files with 20 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/f2fs/f2fs.h
View File

@ -4483,7 +4483,8 @@ static inline bool f2fs_low_mem_mode(struct f2fs_sb_info *sbi)
static inline bool f2fs_may_compress(struct inode *inode)
{
if (IS_SWAPFILE(inode) || f2fs_is_pinned_file(inode) ||
f2fs_is_atomic_file(inode) || f2fs_has_inline_data(inode))
f2fs_is_atomic_file(inode) || f2fs_has_inline_data(inode) ||
f2fs_is_mmap_file(inode))
return false;
return S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode);
}

23
fs/f2fs/file.c
View File

@ -526,7 +526,11 @@ static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
file_accessed(file);
vma->vm_ops = &f2fs_file_vm_ops;
f2fs_down_read(&F2FS_I(inode)->i_sem);
set_inode_flag(inode, FI_MMAP_FILE);
f2fs_up_read(&F2FS_I(inode)->i_sem);
return 0;
}
@ -1919,12 +1923,19 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
int err = f2fs_convert_inline_inode(inode);
if (err)
return err;
if (!f2fs_may_compress(inode))
f2fs_down_write(&F2FS_I(inode)->i_sem);
if (!f2fs_may_compress(inode) ||
(S_ISREG(inode->i_mode) &&
F2FS_HAS_BLOCKS(inode))) {
f2fs_up_write(&F2FS_I(inode)->i_sem);
return -EINVAL;
if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
return -EINVAL;
if (set_compress_context(inode))
return -EOPNOTSUPP;
}
err = set_compress_context(inode);
f2fs_up_write(&F2FS_I(inode)->i_sem);
if (err)
return err;
}
}
@ -3976,6 +3987,7 @@ static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
file_start_write(filp);
inode_lock(inode);
f2fs_down_write(&F2FS_I(inode)->i_sem);
if (f2fs_is_mmap_file(inode) || get_dirty_pages(inode)) {
ret = -EBUSY;
goto out;
@ -3995,6 +4007,7 @@ static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
f2fs_warn(sbi, "compression algorithm is successfully set, "
"but current kernel doesn't support this algorithm.");
out:
f2fs_up_write(&F2FS_I(inode)->i_sem);
inode_unlock(inode);
file_end_write(filp);