[RFC][PATCH 09/10 v1][RESEND] ext4: don't need to writeout all dirty pages in punch hole

Zheng Liu
2012-07-22T07:51:38Z

Now we don't need to writeout all dirty pages when punching a hole. The i_mutex
locking is taken to avoid concurrent writes. In truncate_pagecache_range, all
pages in this hole is released, and ext4_es_remove_space is called to update
extent status tree.

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
---
fs/ext4/extents.c | 28 ++++++++++++----------------
1 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f2c5294..2a526b4 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4529,9 +4529,11 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
loff_t first_page_offset, last_page_offset;
int credits, err = 0;

+ mutex_lock(&inode->i_mutex);
+
/* No need to punch hole beyond i_size */
if (offset >= inode->i_size)
- return 0;
+ goto error;

/*
* If the hole extends beyond i_size, set the hole
@@ -4549,18 +4551,6 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
first_page_offset = first_page << PAGE_CACHE_SHIFT;
last_page_offset = last_page << PAGE_CACHE_SHIFT;

- /*
- * Write out all dirty pages to avoid race conditions
- * Then release them.
- */
- if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
- err = filemap_write_and_wait_range(mapping,
- offset, offset + length - 1);
-
- if (err)
- return err;
- }
-
/* Now release the pages */
if (last_page_offset > first_page_offset) {
truncate_pagecache_range(inode, first_page_offset,
@@ -4572,12 +4562,14 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)

credits = ext4_writepage_trans_blocks(inode);
handle = ext4_journal_start(inode, credits);
- if (IS_ERR(handle))
- return PTR_ERR(handle);
+ if (IS_ERR(handle)) {
+ err = PTR_ERR(handle);
+ goto error;
+ }

err = ext4_orphan_add(handle, inode);
if (err)
- goto out;
+ goto error;

/*
* Now we need to zero out the non-page-aligned data in the
@@ -4652,6 +4644,8 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
ext4_ext_invalidate_cache(inode);
ext4_discard_preallocations(inode);

+ err = ext4_es_remove_space(inode, first_block,
+ stop_block - first_block);
err = ext4_ext_remove_space(inode, first_block, stop_block - 1);

ext4_ext_invalidate_cache(inode);
@@ -4667,6 +4661,8 @@ out:
inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
ext4_mark_inode_dirty(handle, inode);
ext4_journal_stop(handle);
+error:
+ mutex_unlock(&inode->i_mutex);
return err;
}
int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
--
1.7.4.1