ext4: handle EOF correctly in ext4_bio_write_page()
We need to zero out part of a page which beyond EOF before setting uptodate, otherwise, mapread or write will see non-zero data beyond EOF. Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
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@ -385,6 +385,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
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block_end = block_start + blocksize;
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if (block_start >= len) {
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/*
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* Comments copied from block_write_full_page_endio:
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*
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* The page straddles i_size. It must be zeroed out on
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* each and every writepage invocation because it may
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* be mmapped. "A file is mapped in multiples of the
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* page size. For a file that is not a multiple of
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* the page size, the remaining memory is zeroed when
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* mapped, and writes to that region are not written
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* out to the file."
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*/
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zero_user_segment(page, block_start, block_end);
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clear_buffer_dirty(bh);
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set_buffer_uptodate(bh);
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continue;
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