[PATCH 2/6 v5] ext4: fix xfstests 75, 112, 127 punch hole failure
From: Allison Henderson <hidden>
Date: 2011-08-21 02:26:42
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
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 Signed-off-by: Allison Henderson <redacted> --- :100644 100644 4d73e11... cd58117... M fs/ext4/extents.c fs/ext4/extents.c | 48 ++++++++++++++++++++++++++++++------------------ 1 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4d73e11..cd58117 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c@@ -4157,7 +4157,7 @@ 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_block_offset, last_block_offset, page_len; loff_t first_page, last_page, first_page_offset, last_page_offset; int ret, credits, blocks_released, err = 0;
@@ -4206,24 +4206,36 @@ 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 + */ + ext4_discard_partial_page_buffers(handle, + mapping, offset, length, 0); + } 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) + ext4_discard_partial_page_buffers(handle, mapping, + offset, page_len, 0); + + /* + * 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) { + ext4_discard_partial_page_buffers(handle, mapping, + last_page_offset, page_len, 0); } }
--
1.7.1