From ba06208a1315ab2d2217e09c79582b886c9f629e Mon Sep 17 00:00:00 2001 From: Allison Henderson Date: Sat, 3 Sep 2011 11:55:59 -0400 Subject: [PATCH] ext4: fix xfstests 75, 112, 127 punch hole failure This patch addresses a bug found by xfstests 75, 112, 127 when blocksize = 1k This bug happens because the punch hole code only zeros out non block aligned regions of the page. This means that if the blocks are smaller than a page, then the block aligned regions of the page inside the hole are left un-zeroed, and their buffer heads are still mapped. This bug is corrected by using ext4_discard_partial_page_buffers to properly zero the partial page at the head and tail of the hole, and unmap the corresponding buffer heads This patch also addresses a bug reported by Lukas while working on a new patch to add discard support for loop devices using punch hole. The bug happened because of the first and last block number needed to be cast to a larger data type before calculating the byte offset, but since now we only need the byte offsets of the pages, we no longer even need to be calculating the byte offsets of the blocks. The code to do the block offset calculations is removed in this patch. Signed-off-by: Allison Henderson --- fs/ext4/extents.c | 61 ++++++++++++++++++++++++++++++----------------- 1 file changed, 39 insertions(+), 22 deletions(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 57cf568a98ab..18f7e04a4fa3 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4162,17 +4162,14 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length) struct address_space *mapping = inode->i_mapping; struct ext4_map_blocks map; handle_t *handle; - loff_t first_block_offset, last_block_offset, block_len; - loff_t first_page, last_page, first_page_offset, last_page_offset; + loff_t first_page, last_page, page_len; + loff_t first_page_offset, last_page_offset; int ret, credits, blocks_released, err = 0; first_block = (offset + sb->s_blocksize - 1) >> EXT4_BLOCK_SIZE_BITS(sb); last_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb); - first_block_offset = first_block << EXT4_BLOCK_SIZE_BITS(sb); - last_block_offset = last_block << EXT4_BLOCK_SIZE_BITS(sb); - first_page = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; last_page = (offset + length) >> PAGE_CACHE_SHIFT; @@ -4211,24 +4208,44 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length) goto out; /* - * Now we need to zero out the un block aligned data. - * If the file is smaller than a block, just - * zero out the middle + * Now we need to zero out the non-page-aligned data in the + * pages at the start and tail of the hole, and unmap the buffer + * heads for the block aligned regions of the page that were + * completely zeroed. */ - if (first_block > last_block) - ext4_block_zero_page_range(handle, mapping, offset, length); - else { - /* zero out the head of the hole before the first block */ - block_len = first_block_offset - offset; - if (block_len > 0) - ext4_block_zero_page_range(handle, mapping, - offset, block_len); - - /* zero out the tail of the hole after the last block */ - block_len = offset + length - last_block_offset; - if (block_len > 0) { - ext4_block_zero_page_range(handle, mapping, - last_block_offset, block_len); + if (first_page > last_page) { + /* + * If the file space being truncated is contained within a page + * just zero out and unmap the middle of that page + */ + err = ext4_discard_partial_page_buffers(handle, + mapping, offset, length, 0); + + if (err) + goto out; + } else { + /* + * zero out and unmap the partial page that contains + * the start of the hole + */ + page_len = first_page_offset - offset; + if (page_len > 0) { + err = ext4_discard_partial_page_buffers(handle, mapping, + offset, page_len, 0); + if (err) + goto out; + } + + /* + * zero out and unmap the partial page that contains + * the end of the hole + */ + page_len = offset + length - last_page_offset; + if (page_len > 0) { + err = ext4_discard_partial_page_buffers(handle, mapping, + last_page_offset, page_len, 0); + if (err) + goto out; } } -- 2.20.1