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Date: Mon, 28 Feb 2011 20:08:34 -0700
From: Allison Henderson <achender@...ux.vnet.ibm.com>
To: linux-ext4@...r.kernel.org
Subject: [Ext4 punch hole 2/5] Ext4 Punch Hole Support: Clear Hole
This patch adds routines needed to zero out the hole
unblock aligned data of the hole.
The existing ext4_block_truncate_page routine that
is used to zero out unblock aligned data from truncate
has been modified to accept a length parameter, and
renamed to ext4_block_zero_page_range.
The function can now be used to zero out the
head of a block, the tail of a block, or the middle
of a block. The existing ext4_block_truncate_page
has now become a wrapper to this function
Signed-off-by: Allison Henderson <achender@...ibm.com>
---
:100644 100644 3aa0b72... 43a5772... M fs/ext4/ext4.h
:100644 100644 9f7f9e4... 28c9137... M fs/ext4/inode.c
fs/ext4/ext4.h | 2 ++
fs/ext4/inode.c | 33 +++++++++++++++++++++++++++++++--
2 files changed, 33 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3aa0b72..43a5772 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1738,6 +1738,8 @@ extern int ext4_writepage_trans_blocks(struct inode *);
extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
extern int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from);
+extern int ext4_block_zero_page_range(handle_t *handle,
+ struct address_space *mapping, loff_t from, loff_t length);
extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
extern qsize_t *ext4_get_reserved_space(struct inode *inode);
extern void ext4_da_update_reserve_space(struct inode *inode,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9f7f9e4..28c9137 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3988,9 +3988,30 @@ void ext4_set_aops(struct inode *inode)
int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from)
{
+ unsigned offset = from & (PAGE_CACHE_SIZE-1);
+ unsigned length;
+ unsigned blocksize;
+ struct inode *inode = mapping->host;
+
+ blocksize = inode->i_sb->s_blocksize;
+ length = blocksize - (offset & (blocksize - 1));
+
+ return ext4_block_zero_page_range(handle, mapping, from, length);
+}
+
+/*
+ * ext4_block_zero_page_range() zeros out a mapping of length 'length'
+ * starting from file offset 'from'. The range to be zero'd must
+ * be contained with in one block. If the specified range exceeds
+ * the end of the block it will be shortened to end of the block
+ * that cooresponds to 'from'
+ */
+int ext4_block_zero_page_range(handle_t *handle,
+ struct address_space *mapping, loff_t from, loff_t length)
+{
ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
unsigned offset = from & (PAGE_CACHE_SIZE-1);
- unsigned blocksize, length, pos;
+ unsigned blocksize, max, pos;
ext4_lblk_t iblock;
struct inode *inode = mapping->host;
struct buffer_head *bh;
@@ -4003,7 +4024,15 @@ int ext4_block_truncate_page(handle_t *handle,
return -EINVAL;
blocksize = inode->i_sb->s_blocksize;
- length = blocksize - (offset & (blocksize - 1));
+ max = blocksize - (offset & (blocksize - 1));
+
+ /*
+ * correct length if it does not fall between
+ * 'from' and the end of the block
+ */
+ if(length > max || length < 0)
+ length = max;
+
iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
if (!page_has_buffers(page))
--
1.7.1
--
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