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| author | Christoph Hellwig <hch@infradead.org> | 2012-07-03 12:20:00 -0400 |
|---|---|---|
| committer | Ben Myers <bpm@sgi.com> | 2012-07-22 10:42:56 -0500 |
| commit | 6b7a03f03a2f8b1629133e35729eba4727fae3cc (patch) | |
| tree | 4b91f307c89e0c064de577f232913d1fc916cdc8 /fs/xfs/xfs_aops.c | |
| parent | 69ff2826117f1cde9a2491be57a578212bca551e (diff) | |
| download | lwn-6b7a03f03a2f8b1629133e35729eba4727fae3cc.tar.gz lwn-6b7a03f03a2f8b1629133e35729eba4727fae3cc.zip | |
xfs: handle EOF correctly in xfs_vm_writepage
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.
Based on the code in fs/buffer.c and the following ext4 commit:
ext4: handle EOF correctly in ext4_bio_write_page()
And yes, I wish we had a good test case for it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_aops.c')
| -rw-r--r-- | fs/xfs/xfs_aops.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 84e372596d56..91d77ac51bba 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -927,11 +927,26 @@ xfs_vm_writepage( end_index = offset >> PAGE_CACHE_SHIFT; last_index = (offset - 1) >> PAGE_CACHE_SHIFT; if (page->index >= end_index) { - if ((page->index >= end_index + 1) || - !(i_size_read(inode) & (PAGE_CACHE_SIZE - 1))) { + unsigned offset_into_page = offset & (PAGE_CACHE_SIZE - 1); + + /* + * Just skip the page if it is fully outside i_size, e.g. due + * to a truncate operation that is in progress. + */ + if (page->index >= end_index + 1 || offset_into_page == 0) { unlock_page(page); return 0; } + + /* + * The page straddles i_size. It must be zeroed out on each + * and every writepage invocation because it may be mmapped. + * "A file is mapped in multiples of the page size. For a file + * that is not a multiple of the page size, the remaining + * memory is zeroed when mapped, and writes to that region are + * not written out to the file." + */ + zero_user_segment(page, offset_into_page, PAGE_CACHE_SIZE); } end_offset = min_t(unsigned long long, |