v4.19.13 snapshot.
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
new file mode 100644
index 0000000..2f5be02
--- /dev/null
+++ b/fs/ext4/move_extent.c
@@ -0,0 +1,699 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
+ * Written by Takashi Sato <t-sato@yk.jp.nec.com>
+ * Akira Fujita <a-fujita@rs.jp.nec.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/quotaops.h>
+#include <linux/slab.h>
+#include "ext4_jbd2.h"
+#include "ext4.h"
+#include "ext4_extents.h"
+
+/**
+ * get_ext_path - Find an extent path for designated logical block number.
+ *
+ * @inode: an inode which is searched
+ * @lblock: logical block number to find an extent path
+ * @path: pointer to an extent path pointer (for output)
+ *
+ * ext4_find_extent wrapper. Return 0 on success, or a negative error value
+ * on failure.
+ */
+static inline int
+get_ext_path(struct inode *inode, ext4_lblk_t lblock,
+ struct ext4_ext_path **ppath)
+{
+ struct ext4_ext_path *path;
+
+ path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+ if (path[ext_depth(inode)].p_ext == NULL) {
+ ext4_ext_drop_refs(path);
+ kfree(path);
+ *ppath = NULL;
+ return -ENODATA;
+ }
+ *ppath = path;
+ return 0;
+}
+
+/**
+ * ext4_double_down_write_data_sem - Acquire two inodes' write lock
+ * of i_data_sem
+ *
+ * Acquire write lock of i_data_sem of the two inodes
+ */
+void
+ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
+{
+ if (first < second) {
+ down_write(&EXT4_I(first)->i_data_sem);
+ down_write_nested(&EXT4_I(second)->i_data_sem, I_DATA_SEM_OTHER);
+ } else {
+ down_write(&EXT4_I(second)->i_data_sem);
+ down_write_nested(&EXT4_I(first)->i_data_sem, I_DATA_SEM_OTHER);
+
+ }
+}
+
+/**
+ * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
+ *
+ * @orig_inode: original inode structure to be released its lock first
+ * @donor_inode: donor inode structure to be released its lock second
+ * Release write lock of i_data_sem of two inodes (orig and donor).
+ */
+void
+ext4_double_up_write_data_sem(struct inode *orig_inode,
+ struct inode *donor_inode)
+{
+ up_write(&EXT4_I(orig_inode)->i_data_sem);
+ up_write(&EXT4_I(donor_inode)->i_data_sem);
+}
+
+/**
+ * mext_check_coverage - Check that all extents in range has the same type
+ *
+ * @inode: inode in question
+ * @from: block offset of inode
+ * @count: block count to be checked
+ * @unwritten: extents expected to be unwritten
+ * @err: pointer to save error value
+ *
+ * Return 1 if all extents in range has expected type, and zero otherwise.
+ */
+static int
+mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
+ int unwritten, int *err)
+{
+ struct ext4_ext_path *path = NULL;
+ struct ext4_extent *ext;
+ int ret = 0;
+ ext4_lblk_t last = from + count;
+ while (from < last) {
+ *err = get_ext_path(inode, from, &path);
+ if (*err)
+ goto out;
+ ext = path[ext_depth(inode)].p_ext;
+ if (unwritten != ext4_ext_is_unwritten(ext))
+ goto out;
+ from += ext4_ext_get_actual_len(ext);
+ ext4_ext_drop_refs(path);
+ }
+ ret = 1;
+out:
+ ext4_ext_drop_refs(path);
+ kfree(path);
+ return ret;
+}
+
+/**
+ * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
+ *
+ * @inode1: the inode structure
+ * @inode2: the inode structure
+ * @index1: page index
+ * @index2: 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 index1, pgoff_t index2, 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 {
+ swap(index1, index2);
+ mapping[0] = inode2->i_mapping;
+ mapping[1] = inode1->i_mapping;
+ }
+
+ page[0] = grab_cache_page_write_begin(mapping[0], index1, fl);
+ if (!page[0])
+ return -ENOMEM;
+
+ page[1] = grab_cache_page_write_begin(mapping[1], index2, fl);
+ if (!page[1]) {
+ unlock_page(page[0]);
+ put_page(page[0]);
+ return -ENOMEM;
+ }
+ /*
+ * grab_cache_page_write_begin() may not wait on page's writeback if
+ * BDI not demand that. But it is reasonable to be very conservative
+ * here and explicitly wait on page's writeback
+ */
+ wait_on_page_writeback(page[0]);
+ wait_on_page_writeback(page[1]);
+ if (inode1 > inode2)
+ swap(page[0], page[1]);
+
+ 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 = i_blocksize(inode);
+ if (!page_has_buffers(page))
+ create_empty_buffers(page, blocksize, 0);
+
+ head = page_buffers(page);
+ block = (sector_t)page->index << (PAGE_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)) {
+ err = ext4_get_block(inode, block, bh, 0);
+ if (err) {
+ SetPageError(page);
+ return err;
+ }
+ if (!buffer_mapped(bh)) {
+ zero_user(page, block_start, blocksize);
+ 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
+ *
+ * @o_filp: file structure of original file
+ * @donor_inode: donor inode
+ * @orig_page_offset: page index on original file
+ * @donor_page_offset: page index on donor file
+ * @data_offset_in_page: block index where data swapping starts
+ * @block_len_in_page: the number of blocks to be swapped
+ * @unwritten: orig extent is unwritten or not
+ * @err: pointer to save return value
+ *
+ * Save the data in original inode blocks and replace original inode extents
+ * with donor inode extents by calling ext4_swap_extents().
+ * Finally, write out the saved data in new original inode blocks. Return
+ * replaced block count.
+ */
+static int
+move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
+ pgoff_t orig_page_offset, pgoff_t donor_page_offset,
+ int data_offset_in_page,
+ int block_len_in_page, int unwritten, int *err)
+{
+ struct inode *orig_inode = file_inode(o_filp);
+ struct page *pagep[2] = {NULL, NULL};
+ handle_t *handle;
+ ext4_lblk_t orig_blk_offset, donor_blk_offset;
+ unsigned long blocksize = orig_inode->i_sb->s_blocksize;
+ unsigned int tmp_data_size, data_size, replaced_size;
+ int i, err2, jblocks, retries = 0;
+ int replaced_count = 0;
+ int from = data_offset_in_page << orig_inode->i_blkbits;
+ int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
+ struct super_block *sb = orig_inode->i_sb;
+ struct buffer_head *bh = NULL;
+
+ /*
+ * 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, EXT4_HT_MOVE_EXTENTS, jblocks);
+ if (IS_ERR(handle)) {
+ *err = PTR_ERR(handle);
+ return 0;
+ }
+
+ orig_blk_offset = orig_page_offset * blocks_per_page +
+ data_offset_in_page;
+
+ donor_blk_offset = donor_page_offset * blocks_per_page +
+ data_offset_in_page;
+
+ /* Calculate data_size */
+ if ((orig_blk_offset + block_len_in_page - 1) ==
+ ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
+ /* Replace the last block */
+ tmp_data_size = orig_inode->i_size & (blocksize - 1);
+ /*
+ * If data_size equal zero, it shows data_size is multiples of
+ * blocksize. So we set appropriate value.
+ */
+ if (tmp_data_size == 0)
+ tmp_data_size = blocksize;
+
+ data_size = tmp_data_size +
+ ((block_len_in_page - 1) << orig_inode->i_blkbits);
+ } else
+ data_size = block_len_in_page << orig_inode->i_blkbits;
+
+ replaced_size = data_size;
+
+ *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
+ donor_page_offset, pagep);
+ if (unlikely(*err < 0))
+ goto stop_journal;
+ /*
+ * If orig extent was unwritten it can become initialized
+ * at any time after i_data_sem was dropped, in order to
+ * serialize with delalloc we have recheck extent while we
+ * hold page's lock, if it is still the case data copy is not
+ * necessary, just swap data blocks between orig and donor.
+ */
+ if (unwritten) {
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
+ /* If any of extents in range became initialized we have to
+ * fallback to data copying */
+ unwritten = mext_check_coverage(orig_inode, orig_blk_offset,
+ block_len_in_page, 1, err);
+ if (*err)
+ goto drop_data_sem;
+
+ unwritten &= mext_check_coverage(donor_inode, donor_blk_offset,
+ block_len_in_page, 1, err);
+ if (*err)
+ goto drop_data_sem;
+
+ if (!unwritten) {
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
+ goto data_copy;
+ }
+ 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 drop_data_sem;
+ }
+ replaced_count = ext4_swap_extents(handle, orig_inode,
+ donor_inode, orig_blk_offset,
+ donor_blk_offset,
+ block_len_in_page, 1, err);
+ drop_data_sem:
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
+ goto unlock_pages;
+ }
+data_copy:
+ *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;
+ }
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
+ replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode,
+ orig_blk_offset, donor_blk_offset,
+ block_len_in_page, 1, err);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
+ if (*err) {
+ if (replaced_count) {
+ block_len_in_page = replaced_count;
+ replaced_size =
+ block_len_in_page << orig_inode->i_blkbits;
+ } else
+ goto unlock_pages;
+ }
+ /* Perform all necessary steps similar write_begin()/write_end()
+ * but keeping in mind that i_size will not change */
+ if (!page_has_buffers(pagep[0]))
+ create_empty_buffers(pagep[0], 1 << orig_inode->i_blkbits, 0);
+ bh = page_buffers(pagep[0]);
+ 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, orig_blk_offset + i, bh, 0);
+ if (*err < 0)
+ break;
+ bh = bh->b_this_page;
+ }
+ if (!*err)
+ *err = block_commit_write(pagep[0], from, from + replaced_size);
+
+ 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_inode_add_write(handle, orig_inode);
+
+unlock_pages:
+ unlock_page(pagep[0]);
+ put_page(pagep[0]);
+ unlock_page(pagep[1]);
+ put_page(pagep[1]);
+stop_journal:
+ ext4_journal_stop(handle);
+ if (*err == -ENOSPC &&
+ ext4_should_retry_alloc(sb, &retries))
+ goto again;
+ /* Buffer was busy because probably is pinned to journal transaction,
+ * force transaction commit may help to free it. */
+ if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal &&
+ jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal))
+ 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
+ */
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
+ replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode,
+ orig_blk_offset, donor_blk_offset,
+ block_len_in_page, 0, &err2);
+ ext4_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;
+}
+
+/**
+ * mext_check_arguments - Check whether move extent can be done
+ *
+ * @orig_inode: original inode
+ * @donor_inode: donor inode
+ * @orig_start: logical start offset in block for orig
+ * @donor_start: logical start offset in block for donor
+ * @len: the number of blocks to be moved
+ *
+ * Check the arguments of ext4_move_extents() whether the files can be
+ * exchanged with each other.
+ * Return 0 on success, or a negative error value on failure.
+ */
+static int
+mext_check_arguments(struct inode *orig_inode,
+ struct inode *donor_inode, __u64 orig_start,
+ __u64 donor_start, __u64 *len)
+{
+ __u64 orig_eof, donor_eof;
+ unsigned int blkbits = orig_inode->i_blkbits;
+ unsigned int blocksize = 1 << blkbits;
+
+ orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits;
+ donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits;
+
+
+ if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
+ ext4_debug("ext4 move extent: suid or sgid is set"
+ " to donor file [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
+ return -EPERM;
+
+ /* Ext4 move extent does not support swapfile */
+ if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
+ ext4_debug("ext4 move extent: The argument files should "
+ "not be swapfile [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EBUSY;
+ }
+
+ if (ext4_is_quota_file(orig_inode) && ext4_is_quota_file(donor_inode)) {
+ ext4_debug("ext4 move extent: The argument files should "
+ "not be quota files [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EBUSY;
+ }
+
+ /* Ext4 move extent supports only extent based file */
+ if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
+ ext4_debug("ext4 move extent: orig file is not extents "
+ "based file [ino:orig %lu]\n", orig_inode->i_ino);
+ return -EOPNOTSUPP;
+ } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
+ ext4_debug("ext4 move extent: donor file is not extents "
+ "based file [ino:donor %lu]\n", donor_inode->i_ino);
+ return -EOPNOTSUPP;
+ }
+
+ if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
+ ext4_debug("ext4 move extent: File size is 0 byte\n");
+ return -EINVAL;
+ }
+
+ /* Start offset should be same */
+ if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) !=
+ (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) {
+ ext4_debug("ext4 move extent: orig and donor's start "
+ "offsets are not aligned [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ if ((orig_start >= EXT_MAX_BLOCKS) ||
+ (donor_start >= EXT_MAX_BLOCKS) ||
+ (*len > EXT_MAX_BLOCKS) ||
+ (donor_start + *len >= EXT_MAX_BLOCKS) ||
+ (orig_start + *len >= EXT_MAX_BLOCKS)) {
+ ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
+ "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+ if (orig_eof <= orig_start)
+ *len = 0;
+ else if (orig_eof < orig_start + *len - 1)
+ *len = orig_eof - orig_start;
+ if (donor_eof <= donor_start)
+ *len = 0;
+ else if (donor_eof < donor_start + *len - 1)
+ *len = donor_eof - donor_start;
+ if (!*len) {
+ ext4_debug("ext4 move extent: len should not be 0 "
+ "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
+ donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * ext4_move_extents - Exchange the specified range of a file
+ *
+ * @o_filp: file structure of the original file
+ * @d_filp: file structure of the donor file
+ * @orig_blk: start offset in block for orig
+ * @donor_blk: start offset in block for donor
+ * @len: the number of blocks to be moved
+ * @moved_len: moved block length
+ *
+ * This function returns 0 and moved block length is set in moved_len
+ * if succeed, otherwise returns error value.
+ *
+ */
+int
+ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
+ __u64 donor_blk, __u64 len, __u64 *moved_len)
+{
+ struct inode *orig_inode = file_inode(o_filp);
+ struct inode *donor_inode = file_inode(d_filp);
+ struct ext4_ext_path *path = NULL;
+ int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
+ ext4_lblk_t o_end, o_start = orig_blk;
+ ext4_lblk_t d_start = donor_blk;
+ int ret;
+
+ if (orig_inode->i_sb != donor_inode->i_sb) {
+ ext4_debug("ext4 move extent: The argument files "
+ "should be in same FS [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ /* orig and donor should be different inodes */
+ if (orig_inode == donor_inode) {
+ ext4_debug("ext4 move extent: The argument files should not "
+ "be same inode [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ /* Regular file check */
+ if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
+ ext4_debug("ext4 move extent: The argument files should be "
+ "regular file [ino:orig %lu, donor %lu]\n",
+ orig_inode->i_ino, donor_inode->i_ino);
+ return -EINVAL;
+ }
+
+ /* TODO: it's not obvious how to swap blocks for inodes with full
+ journaling enabled */
+ if (ext4_should_journal_data(orig_inode) ||
+ ext4_should_journal_data(donor_inode)) {
+ ext4_msg(orig_inode->i_sb, KERN_ERR,
+ "Online defrag not supported with data journaling");
+ return -EOPNOTSUPP;
+ }
+
+ if (ext4_encrypted_inode(orig_inode) ||
+ ext4_encrypted_inode(donor_inode)) {
+ ext4_msg(orig_inode->i_sb, KERN_ERR,
+ "Online defrag not supported for encrypted files");
+ return -EOPNOTSUPP;
+ }
+
+ /* Protect orig and donor inodes against a truncate */
+ lock_two_nondirectories(orig_inode, donor_inode);
+
+ /* Wait for all existing dio workers */
+ inode_dio_wait(orig_inode);
+ inode_dio_wait(donor_inode);
+
+ /* Protect extent tree against block allocations via delalloc */
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
+ /* Check the filesystem environment whether move_extent can be done */
+ ret = mext_check_arguments(orig_inode, donor_inode, orig_blk,
+ donor_blk, &len);
+ if (ret)
+ goto out;
+ o_end = o_start + len;
+
+ while (o_start < o_end) {
+ struct ext4_extent *ex;
+ ext4_lblk_t cur_blk, next_blk;
+ pgoff_t orig_page_index, donor_page_index;
+ int offset_in_page;
+ int unwritten, cur_len;
+
+ ret = get_ext_path(orig_inode, o_start, &path);
+ if (ret)
+ goto out;
+ ex = path[path->p_depth].p_ext;
+ next_blk = ext4_ext_next_allocated_block(path);
+ cur_blk = le32_to_cpu(ex->ee_block);
+ cur_len = ext4_ext_get_actual_len(ex);
+ /* Check hole before the start pos */
+ if (cur_blk + cur_len - 1 < o_start) {
+ if (next_blk == EXT_MAX_BLOCKS) {
+ o_start = o_end;
+ ret = -ENODATA;
+ goto out;
+ }
+ d_start += next_blk - o_start;
+ o_start = next_blk;
+ continue;
+ /* Check hole after the start pos */
+ } else if (cur_blk > o_start) {
+ /* Skip hole */
+ d_start += cur_blk - o_start;
+ o_start = cur_blk;
+ /* Extent inside requested range ?*/
+ if (cur_blk >= o_end)
+ goto out;
+ } else { /* in_range(o_start, o_blk, o_len) */
+ cur_len += cur_blk - o_start;
+ }
+ unwritten = ext4_ext_is_unwritten(ex);
+ if (o_end - o_start < cur_len)
+ cur_len = o_end - o_start;
+
+ orig_page_index = o_start >> (PAGE_SHIFT -
+ orig_inode->i_blkbits);
+ donor_page_index = d_start >> (PAGE_SHIFT -
+ donor_inode->i_blkbits);
+ offset_in_page = o_start % blocks_per_page;
+ if (cur_len > blocks_per_page- offset_in_page)
+ cur_len = blocks_per_page - offset_in_page;
+ /*
+ * Up semaphore to avoid following problems:
+ * a. transaction deadlock among ext4_journal_start,
+ * ->write_begin via pagefault, and jbd2_journal_commit
+ * b. racing with ->readpage, ->write_begin, and ext4_get_block
+ * in move_extent_per_page
+ */
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
+ /* Swap original branches with new branches */
+ move_extent_per_page(o_filp, donor_inode,
+ orig_page_index, donor_page_index,
+ offset_in_page, cur_len,
+ unwritten, &ret);
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
+ if (ret < 0)
+ break;
+ o_start += cur_len;
+ d_start += cur_len;
+ }
+ *moved_len = o_start - orig_blk;
+ if (*moved_len > len)
+ *moved_len = len;
+
+out:
+ if (*moved_len) {
+ ext4_discard_preallocations(orig_inode);
+ ext4_discard_preallocations(donor_inode);
+ }
+
+ ext4_ext_drop_refs(path);
+ kfree(path);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
+ unlock_two_nondirectories(orig_inode, donor_inode);
+
+ return ret;
+}