Patch "f2fs: compress: fix to call f2fs_wait_on_page_writeback() in f2fs_write_raw_pages()" has been added to the 5.15-stable tree

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This is a note to let you know that I've just added the patch titled

    f2fs: compress: fix to call f2fs_wait_on_page_writeback() in f2fs_write_raw_pages()

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     f2fs-compress-fix-to-call-f2fs_wait_on_page_writebac.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 1e8b92f6fed544531a221c6889ef3a59a4f43cef
Author: Yangtao Li <frank.li@xxxxxxxx>
Date:   Tue Mar 21 01:22:18 2023 +0800

    f2fs: compress: fix to call f2fs_wait_on_page_writeback() in f2fs_write_raw_pages()
    
    [ Upstream commit babedcbac164cec970872b8097401ca913a80e61 ]
    
    BUG_ON() will be triggered when writing files concurrently,
    because the same page is writtenback multiple times.
    
    1597 void folio_end_writeback(struct folio *folio)
    1598 {
                    ......
    1618     if (!__folio_end_writeback(folio))
    1619         BUG();
                    ......
    1625 }
    
    kernel BUG at mm/filemap.c:1619!
    Call Trace:
     <TASK>
     f2fs_write_end_io+0x1a0/0x370
     blk_update_request+0x6c/0x410
     blk_mq_end_request+0x15/0x130
     blk_complete_reqs+0x3c/0x50
     __do_softirq+0xb8/0x29b
     ? sort_range+0x20/0x20
     run_ksoftirqd+0x19/0x20
     smpboot_thread_fn+0x10b/0x1d0
     kthread+0xde/0x110
     ? kthread_complete_and_exit+0x20/0x20
     ret_from_fork+0x22/0x30
     </TASK>
    
    Below is the concurrency scenario:
    
    [Process A]             [Process B]             [Process C]
    f2fs_write_raw_pages()
      - redirty_page_for_writepage()
      - unlock page()
                            f2fs_do_write_data_page()
                              - lock_page()
                              - clear_page_dirty_for_io()
                              - set_page_writeback() [1st writeback]
                                .....
                                - unlock page()
    
                                                    generic_perform_write()
                                                      - f2fs_write_begin()
                                                        - wait_for_stable_page()
    
                                                      - f2fs_write_end()
                                                        - set_page_dirty()
    
      - lock_page()
        - f2fs_do_write_data_page()
          - set_page_writeback() [2st writeback]
    
    This problem was introduced by the previous commit 7377e853967b ("f2fs:
    compress: fix potential deadlock of compress file"). All pagelocks were
    released in f2fs_write_raw_pages(), but whether the page was
    in the writeback state was ignored in the subsequent writing process.
    Let's fix it by waiting for the page to writeback before writing.
    
    Cc: Christoph Hellwig <hch@xxxxxx>
    Fixes: 4c8ff7095bef ("f2fs: support data compression")
    Fixes: 7377e853967b ("f2fs: compress: fix potential deadlock of compress file")
    Signed-off-by: Qi Han <hanqi@xxxxxxxx>
    Signed-off-by: Yangtao Li <frank.li@xxxxxxxx>
    Reviewed-by: Chao Yu <chao@xxxxxxxxxx>
    Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 4fa62f98cb515..455fac164fda0 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1477,6 +1477,12 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
 		if (!PageDirty(cc->rpages[i]))
 			goto continue_unlock;
 
+		if (PageWriteback(cc->rpages[i])) {
+			if (wbc->sync_mode == WB_SYNC_NONE)
+				goto continue_unlock;
+			f2fs_wait_on_page_writeback(cc->rpages[i], DATA, true, true);
+		}
+
 		if (!clear_page_dirty_for_io(cc->rpages[i]))
 			goto continue_unlock;
 



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