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yaml
---
r: 331599
b: refs/heads/master
c: bb55748
h: refs/heads/master
i:
  331597: 57f6b40
  331595: 727e1d0
  331591: f2f6a28
  331583: 6c7fb25
v: v3
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Dmitry Monakhov authored and Theodore Ts'o committed Sep 26, 2012
1 parent 18e190d commit 850d7f7
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Showing 2 changed files with 179 additions and 76 deletions.
2 changes: 1 addition & 1 deletion [refs]
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Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: f066055a3449f0e5b0ae4f3ceab4445bead47638
refs/heads/master: bb5574880574fea38c674942cf0360253a2d60fe
253 changes: 178 additions & 75 deletions trunk/fs/ext4/move_extent.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -735,6 +735,118 @@ mext_replace_branches(handle_t *handle, struct inode *orig_inode,
return replaced_count;
}

/**
* mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
*
* @inode1: the inode structure
* @inode2: the inode structure
* @index: page index
* @page: result page vector
*
* Grab two locked pages for inode's by inode order
*/
static int
mext_page_double_lock(struct inode *inode1, struct inode *inode2,
pgoff_t index, struct page *page[2])
{
struct address_space *mapping[2];
unsigned fl = AOP_FLAG_NOFS;

BUG_ON(!inode1 || !inode2);
if (inode1 < inode2) {
mapping[0] = inode1->i_mapping;
mapping[1] = inode2->i_mapping;
} else {
mapping[0] = inode2->i_mapping;
mapping[1] = inode1->i_mapping;
}

page[0] = grab_cache_page_write_begin(mapping[0], index, fl);
if (!page[0])
return -ENOMEM;

page[1] = grab_cache_page_write_begin(mapping[1], index, fl);
if (!page[1]) {
unlock_page(page[0]);
page_cache_release(page[0]);
return -ENOMEM;
}

if (inode1 > inode2) {
struct page *tmp;
tmp = page[0];
page[0] = page[1];
page[1] = tmp;
}
return 0;
}

/* Force page buffers uptodate w/o dropping page's lock */
static int
mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
{
struct inode *inode = page->mapping->host;
sector_t block;
struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
unsigned int blocksize, block_start, block_end;
int i, err, nr = 0, partial = 0;
BUG_ON(!PageLocked(page));
BUG_ON(PageWriteback(page));

if (PageUptodate(page))
return 0;

blocksize = 1 << inode->i_blkbits;
if (!page_has_buffers(page))
create_empty_buffers(page, blocksize, 0);

head = page_buffers(page);
block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
for (bh = head, block_start = 0; bh != head || !block_start;
block++, block_start = block_end, bh = bh->b_this_page) {
block_end = block_start + blocksize;
if (block_end <= from || block_start >= to) {
if (!buffer_uptodate(bh))
partial = 1;
continue;
}
if (buffer_uptodate(bh))
continue;
if (!buffer_mapped(bh)) {
int err = 0;
err = ext4_get_block(inode, block, bh, 0);
if (err) {
SetPageError(page);
return err;
}
if (!buffer_mapped(bh)) {
zero_user(page, block_start, blocksize);
if (!err)
set_buffer_uptodate(bh);
continue;
}
}
BUG_ON(nr >= MAX_BUF_PER_PAGE);
arr[nr++] = bh;
}
/* No io required */
if (!nr)
goto out;

for (i = 0; i < nr; i++) {
bh = arr[i];
if (!bh_uptodate_or_lock(bh)) {
err = bh_submit_read(bh);
if (err)
return err;
}
}
out:
if (!partial)
SetPageUptodate(page);
return 0;
}

/**
* move_extent_per_page - Move extent data per page
*
Expand All @@ -757,26 +869,24 @@ move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
int block_len_in_page, int uninit, int *err)
{
struct inode *orig_inode = o_filp->f_dentry->d_inode;
struct address_space *mapping = orig_inode->i_mapping;
struct buffer_head *bh;
struct page *page = NULL;
const struct address_space_operations *a_ops = mapping->a_ops;
struct page *pagep[2] = {NULL, NULL};
handle_t *handle;
ext4_lblk_t orig_blk_offset;
long long offs = orig_page_offset << PAGE_CACHE_SHIFT;
unsigned long blocksize = orig_inode->i_sb->s_blocksize;
unsigned int w_flags = 0;
unsigned int tmp_data_size, data_size, replaced_size;
void *fsdata;
int i, jblocks;
int err2 = 0;
int err2, jblocks, retries = 0;
int replaced_count = 0;
int from = data_offset_in_page << orig_inode->i_blkbits;
int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;

/*
* It needs twice the amount of ordinary journal buffers because
* inode and donor_inode may change each different metadata blocks.
*/
again:
*err = 0;
jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
handle = ext4_journal_start(orig_inode, jblocks);
if (IS_ERR(handle)) {
Expand All @@ -790,19 +900,6 @@ move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
orig_blk_offset = orig_page_offset * blocks_per_page +
data_offset_in_page;

/*
* If orig extent is uninitialized one,
* it's not necessary force the page into memory
* and then force it to be written out again.
* Just swap data blocks between orig and donor.
*/
if (uninit) {
replaced_count = mext_replace_branches(handle, orig_inode,
donor_inode, orig_blk_offset,
block_len_in_page, err);
goto out2;
}

offs = (long long)orig_blk_offset << orig_inode->i_blkbits;

/* Calculate data_size */
Expand All @@ -824,75 +921,81 @@ move_extent_per_page(struct file *o_filp, struct inode *donor_inode,

replaced_size = data_size;

*err = a_ops->write_begin(o_filp, mapping, offs, data_size, w_flags,
&page, &fsdata);
*err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
pagep);
if (unlikely(*err < 0))
goto out;
goto stop_journal;

if (!PageUptodate(page)) {
mapping->a_ops->readpage(o_filp, page);
lock_page(page);
*err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
if (*err)
goto unlock_pages;

/* At this point all buffers in range are uptodate, old mapping layout
* is no longer required, try to drop it now. */
if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
(page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
*err = -EBUSY;
goto unlock_pages;
}

/*
* try_to_release_page() doesn't call releasepage in writeback mode.
* We should care about the order of writing to the same file
* by multiple move extent processes.
* It needs to call wait_on_page_writeback() to wait for the
* writeback of the page.
*/
wait_on_page_writeback(page);

/* Release old bh and drop refs */
try_to_release_page(page, 0);

replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
orig_blk_offset, block_len_in_page,
&err2);
if (err2) {
orig_blk_offset,
block_len_in_page, err);
if (*err) {
if (replaced_count) {
block_len_in_page = replaced_count;
replaced_size =
block_len_in_page << orig_inode->i_blkbits;
} else
goto out;
goto unlock_pages;
}
/* Perform all necessary steps similar write_begin()/write_end()
* but keeping in mind that i_size will not change */
*err = __block_write_begin(pagep[0], from, from + replaced_size,
ext4_get_block);
if (!*err)
*err = block_commit_write(pagep[0], from, from + replaced_size);

if (!page_has_buffers(page))
create_empty_buffers(page, 1 << orig_inode->i_blkbits, 0);

bh = page_buffers(page);
for (i = 0; i < data_offset_in_page; i++)
bh = bh->b_this_page;

for (i = 0; i < block_len_in_page; i++) {
*err = ext4_get_block(orig_inode,
(sector_t)(orig_blk_offset + i), bh, 0);
if (*err < 0)
goto out;

if (bh->b_this_page != NULL)
bh = bh->b_this_page;
}

*err = a_ops->write_end(o_filp, mapping, offs, data_size, replaced_size,
page, fsdata);
page = NULL;

out:
if (unlikely(page)) {
if (PageLocked(page))
unlock_page(page);
page_cache_release(page);
ext4_journal_stop(handle);
}
out2:
if (unlikely(*err < 0))
goto repair_branches;

/* Even in case of data=writeback it is reasonable to pin
* inode to transaction, to prevent unexpected data loss */
*err = ext4_jbd2_file_inode(handle, orig_inode);

unlock_pages:
unlock_page(pagep[0]);
page_cache_release(pagep[0]);
unlock_page(pagep[1]);
page_cache_release(pagep[1]);
stop_journal:
ext4_journal_stop(handle);

if (err2)
*err = err2;

/* Buffer was busy because probably is pinned to journal transaction,
* force transaction commit may help to free it. */
if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb,
&retries))
goto again;
return replaced_count;

repair_branches:
/*
* This should never ever happen!
* Extents are swapped already, but we are not able to copy data.
* Try to swap extents to it's original places
*/
double_down_write_data_sem(orig_inode, donor_inode);
replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
orig_blk_offset,
block_len_in_page, &err2);
double_up_write_data_sem(orig_inode, donor_inode);
if (replaced_count != block_len_in_page) {
EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
"Unable to copy data block,"
" data will be lost.");
*err = -EIO;
}
replaced_count = 0;
goto unlock_pages;
}

/**
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