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
*
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)) {
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 */
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;
}
/**
projects / users / willy / pagecache.git / commitdiff