[RFC][PATCH 06/10 v1][RESEND] ext4: reimplement fiemap on extent status tree

Zheng Liu
2012-07-22T07:51:32Z

This patch reimplements fiemap on extent status tree.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
---
fs/ext4/extents.c | 186 +++++++----------------------------------------------
1 files changed, 23 insertions(+), 163 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0747917..06ca2a3 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4501,193 +4501,53 @@ static int ext4_ext_fiemap_cb(struct inode *inode, ext4_lblk_t next,
struct ext4_ext_cache *newex, struct ext4_extent *ex,
void *data)
{
+ struct extent_status es;
__u64 logical;
__u64 physical;
__u64 length;
__u32 flags = 0;
+ ext4_lblk_t next_del;
int ret = 0;
struct fiemap_extent_info *fieinfo = data;
unsigned char blksize_bits;

- blksize_bits = inode->i_sb->s_blocksize_bits;
- logical = (__u64)newex->ec_block << blksize_bits;
+ es.start = newex->ec_block;
+ down_read(&EXT4_I(inode)->i_data_sem);
+ next_del = ext4_es_find_extent(inode, &es);
+ up_read(&EXT4_I(inode)->i_data_sem);

+ next = min(next_del, next);
if (newex->ec_start == 0) {
/*
* No extent in extent-tree contains block @newex->ec_start,
* then the block may stay in 1)a hole or 2)delayed-extent.
- *
- * Holes or delayed-extents are processed as follows.
- * 1. lookup dirty pages with specified range in pagecache.
- * If no page is got, then there is no delayed-extent and
- * return with EXT_CONTINUE.
- * 2. find the 1st mapped buffer,
- * 3. check if the mapped buffer is both in the request range
- * and a delayed buffer. If not, there is no delayed-extent,
- * then return.
- * 4. a delayed-extent is found, the extent will be collected.
*/
- ext4_lblk_t end = 0;
- pgoff_t last_offset;
- pgoff_t offset;
- pgoff_t index;
- pgoff_t start_index = 0;
- struct page **pages = NULL;
- struct buffer_head *bh = NULL;
- struct buffer_head *head = NULL;
- unsigned int nr_pages = PAGE_SIZE / sizeof(struct page *);
-
- pages = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (pages == NULL)
- return -ENOMEM;
-
- offset = logical >> PAGE_SHIFT;
-repeat:
- last_offset = offset;
- head = NULL;
- ret = find_get_pages_tag(inode->i_mapping, &offset,
- PAGECACHE_TAG_DIRTY, nr_pages, pages);
-
- if (!(flags & FIEMAP_EXTENT_DELALLOC)) {
- /* First time, try to find a mapped buffer. */
- if (ret == 0) {
-out:
- for (index = 0; index < ret; index++)
- page_cache_release(pages[index]);
- /* just a hole. */
- kfree(pages);
- return EXT_CONTINUE;
- }
- index = 0;
-
-next_page:
- /* Try to find the 1st mapped buffer. */
- end = ((__u64)pages[index]->index << PAGE_SHIFT) >>
- blksize_bits;
- if (!page_has_buffers(pages[index]))
- goto out;
- head = page_buffers(pages[index]);
- if (!head)
- goto out;
-
- index++;
- bh = head;
- do {
- if (end >= newex->ec_block +
- newex->ec_len)
- /* The buffer is out of
- * the request range.
- */
- goto out;
-
- if (buffer_mapped(bh) &&
- end >= newex->ec_block) {
- start_index = index - 1;
- /* get the 1st mapped buffer. */
- goto found_mapped_buffer;
- }
-
- bh = bh->b_this_page;
- end++;
- } while (bh != head);
-
- /* No mapped buffer in the range found in this page,
- * We need to look up next page.
- */
- if (index >= ret) {
- /* There is no page left, but we need to limit
- * newex->ec_len.
- */
- newex->ec_len = end - newex->ec_block;
- goto out;
- }
- goto next_page;
- } else {
- /*Find contiguous delayed buffers. */
- if (ret > 0 && pages[0]->index == last_offset)
- head = page_buffers(pages[0]);
- bh = head;
- index = 1;
- start_index = 0;
- }
-
-found_mapped_buffer:
- if (bh != NULL && buffer_delay(bh)) {
- /* 1st or contiguous delayed buffer found. */
- if (!(flags & FIEMAP_EXTENT_DELALLOC)) {
- /*
- * 1st delayed buffer found, record
- * the start of extent.
- */
- flags |= FIEMAP_EXTENT_DELALLOC;
- newex->ec_block = end;
- logical = (__u64)end << blksize_bits;
- }
- /* Find contiguous delayed buffers. */
- do {
- if (!buffer_delay(bh))
- goto found_delayed_extent;
- bh = bh->b_this_page;
- end++;
- } while (bh != head);
-
- for (; index < ret; index++) {
- if (!page_has_buffers(pages[index])) {
- bh = NULL;
- break;
- }
- head = page_buffers(pages[index]);
- if (!head) {
- bh = NULL;
- break;
- }
-
- if (pages[index]->index !=
- pages[start_index]->index + index
- - start_index) {
- /* Blocks are not contiguous. */
- bh = NULL;
- break;
- }
- bh = head;
- do {
- if (!buffer_delay(bh))
- /* Delayed-extent ends. */
- goto found_delayed_extent;
- bh = bh->b_this_page;
- end++;
- } while (bh != head);
- }
- } else if (!(flags & FIEMAP_EXTENT_DELALLOC))
- /* a hole found. */
- goto out;
-
-found_delayed_extent:
- newex->ec_len = min(end - newex->ec_block,
- (ext4_lblk_t)EXT_INIT_MAX_LEN);
- if (ret == nr_pages && bh != NULL &&
- newex->ec_len < EXT_INIT_MAX_LEN &&
- buffer_delay(bh)) {
- /* Have not collected an extent and continue. */
- for (index = 0; index < ret; index++)
- page_cache_release(pages[index]);
- goto repeat;
+ if (es.len == 0)
+ /* A hole found. */
+ return EXT_CONTINUE;
+
+ if (es.start > newex->ec_block) {
+ /* A hole found. */
+ newex->ec_len = min(es.start - newex->ec_block,
+ newex->ec_len);
+ return EXT_CONTINUE;
}

- for (index = 0; index < ret; index++)
- page_cache_release(pages[index]);
- kfree(pages);
+ flags |= FIEMAP_EXTENT_DELALLOC;
+ newex->ec_len = es.start + es.len - newex->ec_block;
}

- physical = (__u64)newex->ec_start << blksize_bits;
- length = (__u64)newex->ec_len << blksize_bits;