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ext4: fix nomblk_io_submit option so it correctly converts uninit blocks

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Bug discovered by Jan Kara:

Finally, commit 1449032be17abb69116dbc393f67ceb8bd034f92 returned back
the old IO submission code but apparently it forgot to return the old
handling of uninitialized buffers so we unconditionnaly call
block_write_full_page() without specifying end_io function. So AFAICS
we never convert unwritten extents to written in some cases. For
example when I mount the fs as: mount -t ext4 -o
nomblk_io_submit,dioread_nolock /dev/ubdb /mnt and do
        int fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0600);
        char buf[1024];
        memset(buf, 'a', sizeof(buf));
        fallocate(fd, 0, 0, 16384);
        write(fd, buf, sizeof(buf));

I get a file full of zeros (after remounting the filesystem so that
pagecache is dropped) instead of seeing the first KB contain 'a's.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
This commit is contained in:
Theodore Ts'o 2011-08-13 12:58:21 -04:00
parent 32c80b32c0
commit 9dd75f1f1a
1 changed files with 6 additions and 1 deletions
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7
fs/ext4/inode.c
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@ -1291,7 +1291,12 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
err = ext4_bio_write_page(&io_submit, page,
len, mpd->wbc);
else
else if (buffer_uninit(page_bufs)) {
ext4_set_bh_endio(page_bufs, inode);
err = block_write_full_page_endio(page,
noalloc_get_block_write,
mpd->wbc, ext4_end_io_buffer_write);
} else
err = block_write_full_page(page,
noalloc_get_block_write, mpd->wbc);