On 2022/3/18 9:23, Fengnan Chang wrote:
When compressed file has blocks, f2fs_ioc_start_atomic_write will succeed, but compressed flag will be remained in inode. If write partial compreseed cluster and commit atomic write will cause data corruption.This is the reproduction process: Step 1: create a compressed file ,write 64K data , call fsync(), then the blocks are write as compressed cluster. Step2: iotcl(F2FS_IOC_START_ATOMIC_WRITE) --- this should be fail, but not. write page 0 and page 3. iotcl(F2FS_IOC_COMMIT_ATOMIC_WRITE) -- page 0 and 3 write as normal file, Step3: drop cache. read page 0-4 -- Since page 0 has a valid block address, read as non-compressed cluster, page 1 and 2 will be filled with compressed data or zero. The root cause is, after commit 7eab7a696827 ("f2fs: compress: remove unneeded read when rewrite whole cluster"), in step 2, f2fs_write_begin() only set target page dirty, and in f2fs_commit_inmem_pages(), we will write partial raw pages into compressed cluster, result in corrupting compressed cluster layout. Fixes: 4c8ff7095bef ("f2fs: support data compression") Fixes: 7eab7a696827 ("f2fs: compress: remove unneeded read when rewrite whole cluster") Reported-by: kernel test robot <[email protected]> Reported-by: Dan Carpenter <[email protected]> Signed-off-by: Fengnan Chang <[email protected]>
Reviewed-by: Chao Yu <[email protected]> Thanks, _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
