cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
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move_extent.c (21372B)


      1// SPDX-License-Identifier: LGPL-2.1
      2/*
      3 * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
      4 * Written by Takashi Sato <t-sato@yk.jp.nec.com>
      5 *            Akira Fujita <a-fujita@rs.jp.nec.com>
      6 */
      7
      8#include <linux/fs.h>
      9#include <linux/quotaops.h>
     10#include <linux/slab.h>
     11#include <linux/sched/mm.h>
     12#include "ext4_jbd2.h"
     13#include "ext4.h"
     14#include "ext4_extents.h"
     15
     16/**
     17 * get_ext_path() - Find an extent path for designated logical block number.
     18 * @inode:	inode to be searched
     19 * @lblock:	logical block number to find an extent path
     20 * @ppath:	pointer to an extent path pointer (for output)
     21 *
     22 * ext4_find_extent wrapper. Return 0 on success, or a negative error value
     23 * on failure.
     24 */
     25static inline int
     26get_ext_path(struct inode *inode, ext4_lblk_t lblock,
     27		struct ext4_ext_path **ppath)
     28{
     29	struct ext4_ext_path *path;
     30
     31	path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE);
     32	if (IS_ERR(path))
     33		return PTR_ERR(path);
     34	if (path[ext_depth(inode)].p_ext == NULL) {
     35		ext4_ext_drop_refs(path);
     36		kfree(path);
     37		*ppath = NULL;
     38		return -ENODATA;
     39	}
     40	*ppath = path;
     41	return 0;
     42}
     43
     44/**
     45 * ext4_double_down_write_data_sem() - write lock two inodes's i_data_sem
     46 * @first: inode to be locked
     47 * @second: inode to be locked
     48 *
     49 * Acquire write lock of i_data_sem of the two inodes
     50 */
     51void
     52ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
     53{
     54	if (first < second) {
     55		down_write(&EXT4_I(first)->i_data_sem);
     56		down_write_nested(&EXT4_I(second)->i_data_sem, I_DATA_SEM_OTHER);
     57	} else {
     58		down_write(&EXT4_I(second)->i_data_sem);
     59		down_write_nested(&EXT4_I(first)->i_data_sem, I_DATA_SEM_OTHER);
     60
     61	}
     62}
     63
     64/**
     65 * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
     66 *
     67 * @orig_inode:		original inode structure to be released its lock first
     68 * @donor_inode:	donor inode structure to be released its lock second
     69 * Release write lock of i_data_sem of two inodes (orig and donor).
     70 */
     71void
     72ext4_double_up_write_data_sem(struct inode *orig_inode,
     73			      struct inode *donor_inode)
     74{
     75	up_write(&EXT4_I(orig_inode)->i_data_sem);
     76	up_write(&EXT4_I(donor_inode)->i_data_sem);
     77}
     78
     79/**
     80 * mext_check_coverage - Check that all extents in range has the same type
     81 *
     82 * @inode:		inode in question
     83 * @from:		block offset of inode
     84 * @count:		block count to be checked
     85 * @unwritten:		extents expected to be unwritten
     86 * @err:		pointer to save error value
     87 *
     88 * Return 1 if all extents in range has expected type, and zero otherwise.
     89 */
     90static int
     91mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
     92		    int unwritten, int *err)
     93{
     94	struct ext4_ext_path *path = NULL;
     95	struct ext4_extent *ext;
     96	int ret = 0;
     97	ext4_lblk_t last = from + count;
     98	while (from < last) {
     99		*err = get_ext_path(inode, from, &path);
    100		if (*err)
    101			goto out;
    102		ext = path[ext_depth(inode)].p_ext;
    103		if (unwritten != ext4_ext_is_unwritten(ext))
    104			goto out;
    105		from += ext4_ext_get_actual_len(ext);
    106		ext4_ext_drop_refs(path);
    107	}
    108	ret = 1;
    109out:
    110	ext4_ext_drop_refs(path);
    111	kfree(path);
    112	return ret;
    113}
    114
    115/**
    116 * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
    117 *
    118 * @inode1:	the inode structure
    119 * @inode2:	the inode structure
    120 * @index1:	page index
    121 * @index2:	page index
    122 * @page:	result page vector
    123 *
    124 * Grab two locked pages for inode's by inode order
    125 */
    126static int
    127mext_page_double_lock(struct inode *inode1, struct inode *inode2,
    128		      pgoff_t index1, pgoff_t index2, struct page *page[2])
    129{
    130	struct address_space *mapping[2];
    131	unsigned int flags;
    132
    133	BUG_ON(!inode1 || !inode2);
    134	if (inode1 < inode2) {
    135		mapping[0] = inode1->i_mapping;
    136		mapping[1] = inode2->i_mapping;
    137	} else {
    138		swap(index1, index2);
    139		mapping[0] = inode2->i_mapping;
    140		mapping[1] = inode1->i_mapping;
    141	}
    142
    143	flags = memalloc_nofs_save();
    144	page[0] = grab_cache_page_write_begin(mapping[0], index1);
    145	if (!page[0]) {
    146		memalloc_nofs_restore(flags);
    147		return -ENOMEM;
    148	}
    149
    150	page[1] = grab_cache_page_write_begin(mapping[1], index2);
    151	memalloc_nofs_restore(flags);
    152	if (!page[1]) {
    153		unlock_page(page[0]);
    154		put_page(page[0]);
    155		return -ENOMEM;
    156	}
    157	/*
    158	 * grab_cache_page_write_begin() may not wait on page's writeback if
    159	 * BDI not demand that. But it is reasonable to be very conservative
    160	 * here and explicitly wait on page's writeback
    161	 */
    162	wait_on_page_writeback(page[0]);
    163	wait_on_page_writeback(page[1]);
    164	if (inode1 > inode2)
    165		swap(page[0], page[1]);
    166
    167	return 0;
    168}
    169
    170/* Force page buffers uptodate w/o dropping page's lock */
    171static int
    172mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
    173{
    174	struct inode *inode = page->mapping->host;
    175	sector_t block;
    176	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
    177	unsigned int blocksize, block_start, block_end;
    178	int i, err,  nr = 0, partial = 0;
    179	BUG_ON(!PageLocked(page));
    180	BUG_ON(PageWriteback(page));
    181
    182	if (PageUptodate(page))
    183		return 0;
    184
    185	blocksize = i_blocksize(inode);
    186	if (!page_has_buffers(page))
    187		create_empty_buffers(page, blocksize, 0);
    188
    189	head = page_buffers(page);
    190	block = (sector_t)page->index << (PAGE_SHIFT - inode->i_blkbits);
    191	for (bh = head, block_start = 0; bh != head || !block_start;
    192	     block++, block_start = block_end, bh = bh->b_this_page) {
    193		block_end = block_start + blocksize;
    194		if (block_end <= from || block_start >= to) {
    195			if (!buffer_uptodate(bh))
    196				partial = 1;
    197			continue;
    198		}
    199		if (buffer_uptodate(bh))
    200			continue;
    201		if (!buffer_mapped(bh)) {
    202			err = ext4_get_block(inode, block, bh, 0);
    203			if (err) {
    204				SetPageError(page);
    205				return err;
    206			}
    207			if (!buffer_mapped(bh)) {
    208				zero_user(page, block_start, blocksize);
    209				set_buffer_uptodate(bh);
    210				continue;
    211			}
    212		}
    213		BUG_ON(nr >= MAX_BUF_PER_PAGE);
    214		arr[nr++] = bh;
    215	}
    216	/* No io required */
    217	if (!nr)
    218		goto out;
    219
    220	for (i = 0; i < nr; i++) {
    221		bh = arr[i];
    222		if (!bh_uptodate_or_lock(bh)) {
    223			err = ext4_read_bh(bh, 0, NULL);
    224			if (err)
    225				return err;
    226		}
    227	}
    228out:
    229	if (!partial)
    230		SetPageUptodate(page);
    231	return 0;
    232}
    233
    234/**
    235 * move_extent_per_page - Move extent data per page
    236 *
    237 * @o_filp:			file structure of original file
    238 * @donor_inode:		donor inode
    239 * @orig_page_offset:		page index on original file
    240 * @donor_page_offset:		page index on donor file
    241 * @data_offset_in_page:	block index where data swapping starts
    242 * @block_len_in_page:		the number of blocks to be swapped
    243 * @unwritten:			orig extent is unwritten or not
    244 * @err:			pointer to save return value
    245 *
    246 * Save the data in original inode blocks and replace original inode extents
    247 * with donor inode extents by calling ext4_swap_extents().
    248 * Finally, write out the saved data in new original inode blocks. Return
    249 * replaced block count.
    250 */
    251static int
    252move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
    253		     pgoff_t orig_page_offset, pgoff_t donor_page_offset,
    254		     int data_offset_in_page,
    255		     int block_len_in_page, int unwritten, int *err)
    256{
    257	struct inode *orig_inode = file_inode(o_filp);
    258	struct page *pagep[2] = {NULL, NULL};
    259	handle_t *handle;
    260	ext4_lblk_t orig_blk_offset, donor_blk_offset;
    261	unsigned long blocksize = orig_inode->i_sb->s_blocksize;
    262	unsigned int tmp_data_size, data_size, replaced_size;
    263	int i, err2, jblocks, retries = 0;
    264	int replaced_count = 0;
    265	int from = data_offset_in_page << orig_inode->i_blkbits;
    266	int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
    267	struct super_block *sb = orig_inode->i_sb;
    268	struct buffer_head *bh = NULL;
    269
    270	/*
    271	 * It needs twice the amount of ordinary journal buffers because
    272	 * inode and donor_inode may change each different metadata blocks.
    273	 */
    274again:
    275	*err = 0;
    276	jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
    277	handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks);
    278	if (IS_ERR(handle)) {
    279		*err = PTR_ERR(handle);
    280		return 0;
    281	}
    282
    283	orig_blk_offset = orig_page_offset * blocks_per_page +
    284		data_offset_in_page;
    285
    286	donor_blk_offset = donor_page_offset * blocks_per_page +
    287		data_offset_in_page;
    288
    289	/* Calculate data_size */
    290	if ((orig_blk_offset + block_len_in_page - 1) ==
    291	    ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
    292		/* Replace the last block */
    293		tmp_data_size = orig_inode->i_size & (blocksize - 1);
    294		/*
    295		 * If data_size equal zero, it shows data_size is multiples of
    296		 * blocksize. So we set appropriate value.
    297		 */
    298		if (tmp_data_size == 0)
    299			tmp_data_size = blocksize;
    300
    301		data_size = tmp_data_size +
    302			((block_len_in_page - 1) << orig_inode->i_blkbits);
    303	} else
    304		data_size = block_len_in_page << orig_inode->i_blkbits;
    305
    306	replaced_size = data_size;
    307
    308	*err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
    309				     donor_page_offset, pagep);
    310	if (unlikely(*err < 0))
    311		goto stop_journal;
    312	/*
    313	 * If orig extent was unwritten it can become initialized
    314	 * at any time after i_data_sem was dropped, in order to
    315	 * serialize with delalloc we have recheck extent while we
    316	 * hold page's lock, if it is still the case data copy is not
    317	 * necessary, just swap data blocks between orig and donor.
    318	 */
    319	if (unwritten) {
    320		ext4_double_down_write_data_sem(orig_inode, donor_inode);
    321		/* If any of extents in range became initialized we have to
    322		 * fallback to data copying */
    323		unwritten = mext_check_coverage(orig_inode, orig_blk_offset,
    324						block_len_in_page, 1, err);
    325		if (*err)
    326			goto drop_data_sem;
    327
    328		unwritten &= mext_check_coverage(donor_inode, donor_blk_offset,
    329						 block_len_in_page, 1, err);
    330		if (*err)
    331			goto drop_data_sem;
    332
    333		if (!unwritten) {
    334			ext4_double_up_write_data_sem(orig_inode, donor_inode);
    335			goto data_copy;
    336		}
    337		if ((page_has_private(pagep[0]) &&
    338		     !try_to_release_page(pagep[0], 0)) ||
    339		    (page_has_private(pagep[1]) &&
    340		     !try_to_release_page(pagep[1], 0))) {
    341			*err = -EBUSY;
    342			goto drop_data_sem;
    343		}
    344		replaced_count = ext4_swap_extents(handle, orig_inode,
    345						   donor_inode, orig_blk_offset,
    346						   donor_blk_offset,
    347						   block_len_in_page, 1, err);
    348	drop_data_sem:
    349		ext4_double_up_write_data_sem(orig_inode, donor_inode);
    350		goto unlock_pages;
    351	}
    352data_copy:
    353	*err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
    354	if (*err)
    355		goto unlock_pages;
    356
    357	/* At this point all buffers in range are uptodate, old mapping layout
    358	 * is no longer required, try to drop it now. */
    359	if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
    360	    (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
    361		*err = -EBUSY;
    362		goto unlock_pages;
    363	}
    364	ext4_double_down_write_data_sem(orig_inode, donor_inode);
    365	replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode,
    366					       orig_blk_offset, donor_blk_offset,
    367					   block_len_in_page, 1, err);
    368	ext4_double_up_write_data_sem(orig_inode, donor_inode);
    369	if (*err) {
    370		if (replaced_count) {
    371			block_len_in_page = replaced_count;
    372			replaced_size =
    373				block_len_in_page << orig_inode->i_blkbits;
    374		} else
    375			goto unlock_pages;
    376	}
    377	/* Perform all necessary steps similar write_begin()/write_end()
    378	 * but keeping in mind that i_size will not change */
    379	if (!page_has_buffers(pagep[0]))
    380		create_empty_buffers(pagep[0], 1 << orig_inode->i_blkbits, 0);
    381	bh = page_buffers(pagep[0]);
    382	for (i = 0; i < data_offset_in_page; i++)
    383		bh = bh->b_this_page;
    384	for (i = 0; i < block_len_in_page; i++) {
    385		*err = ext4_get_block(orig_inode, orig_blk_offset + i, bh, 0);
    386		if (*err < 0)
    387			break;
    388		bh = bh->b_this_page;
    389	}
    390	if (!*err)
    391		*err = block_commit_write(pagep[0], from, from + replaced_size);
    392
    393	if (unlikely(*err < 0))
    394		goto repair_branches;
    395
    396	/* Even in case of data=writeback it is reasonable to pin
    397	 * inode to transaction, to prevent unexpected data loss */
    398	*err = ext4_jbd2_inode_add_write(handle, orig_inode,
    399			(loff_t)orig_page_offset << PAGE_SHIFT, replaced_size);
    400
    401unlock_pages:
    402	unlock_page(pagep[0]);
    403	put_page(pagep[0]);
    404	unlock_page(pagep[1]);
    405	put_page(pagep[1]);
    406stop_journal:
    407	ext4_journal_stop(handle);
    408	if (*err == -ENOSPC &&
    409	    ext4_should_retry_alloc(sb, &retries))
    410		goto again;
    411	/* Buffer was busy because probably is pinned to journal transaction,
    412	 * force transaction commit may help to free it. */
    413	if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal &&
    414	    jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal))
    415		goto again;
    416	return replaced_count;
    417
    418repair_branches:
    419	/*
    420	 * This should never ever happen!
    421	 * Extents are swapped already, but we are not able to copy data.
    422	 * Try to swap extents to it's original places
    423	 */
    424	ext4_double_down_write_data_sem(orig_inode, donor_inode);
    425	replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode,
    426					       orig_blk_offset, donor_blk_offset,
    427					   block_len_in_page, 0, &err2);
    428	ext4_double_up_write_data_sem(orig_inode, donor_inode);
    429	if (replaced_count != block_len_in_page) {
    430		ext4_error_inode_block(orig_inode, (sector_t)(orig_blk_offset),
    431				       EIO, "Unable to copy data block,"
    432				       " data will be lost.");
    433		*err = -EIO;
    434	}
    435	replaced_count = 0;
    436	goto unlock_pages;
    437}
    438
    439/**
    440 * mext_check_arguments - Check whether move extent can be done
    441 *
    442 * @orig_inode:		original inode
    443 * @donor_inode:	donor inode
    444 * @orig_start:		logical start offset in block for orig
    445 * @donor_start:	logical start offset in block for donor
    446 * @len:		the number of blocks to be moved
    447 *
    448 * Check the arguments of ext4_move_extents() whether the files can be
    449 * exchanged with each other.
    450 * Return 0 on success, or a negative error value on failure.
    451 */
    452static int
    453mext_check_arguments(struct inode *orig_inode,
    454		     struct inode *donor_inode, __u64 orig_start,
    455		     __u64 donor_start, __u64 *len)
    456{
    457	__u64 orig_eof, donor_eof;
    458	unsigned int blkbits = orig_inode->i_blkbits;
    459	unsigned int blocksize = 1 << blkbits;
    460
    461	orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits;
    462	donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits;
    463
    464
    465	if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
    466		ext4_debug("ext4 move extent: suid or sgid is set"
    467			   " to donor file [ino:orig %lu, donor %lu]\n",
    468			   orig_inode->i_ino, donor_inode->i_ino);
    469		return -EINVAL;
    470	}
    471
    472	if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
    473		return -EPERM;
    474
    475	/* Ext4 move extent does not support swapfile */
    476	if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
    477		ext4_debug("ext4 move extent: The argument files should "
    478			"not be swapfile [ino:orig %lu, donor %lu]\n",
    479			orig_inode->i_ino, donor_inode->i_ino);
    480		return -EBUSY;
    481	}
    482
    483	if (ext4_is_quota_file(orig_inode) && ext4_is_quota_file(donor_inode)) {
    484		ext4_debug("ext4 move extent: The argument files should "
    485			"not be quota files [ino:orig %lu, donor %lu]\n",
    486			orig_inode->i_ino, donor_inode->i_ino);
    487		return -EBUSY;
    488	}
    489
    490	/* Ext4 move extent supports only extent based file */
    491	if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
    492		ext4_debug("ext4 move extent: orig file is not extents "
    493			"based file [ino:orig %lu]\n", orig_inode->i_ino);
    494		return -EOPNOTSUPP;
    495	} else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
    496		ext4_debug("ext4 move extent: donor file is not extents "
    497			"based file [ino:donor %lu]\n", donor_inode->i_ino);
    498		return -EOPNOTSUPP;
    499	}
    500
    501	if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
    502		ext4_debug("ext4 move extent: File size is 0 byte\n");
    503		return -EINVAL;
    504	}
    505
    506	/* Start offset should be same */
    507	if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) !=
    508	    (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) {
    509		ext4_debug("ext4 move extent: orig and donor's start "
    510			"offsets are not aligned [ino:orig %lu, donor %lu]\n",
    511			orig_inode->i_ino, donor_inode->i_ino);
    512		return -EINVAL;
    513	}
    514
    515	if ((orig_start >= EXT_MAX_BLOCKS) ||
    516	    (donor_start >= EXT_MAX_BLOCKS) ||
    517	    (*len > EXT_MAX_BLOCKS) ||
    518	    (donor_start + *len >= EXT_MAX_BLOCKS) ||
    519	    (orig_start + *len >= EXT_MAX_BLOCKS))  {
    520		ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
    521			"[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
    522			orig_inode->i_ino, donor_inode->i_ino);
    523		return -EINVAL;
    524	}
    525	if (orig_eof <= orig_start)
    526		*len = 0;
    527	else if (orig_eof < orig_start + *len - 1)
    528		*len = orig_eof - orig_start;
    529	if (donor_eof <= donor_start)
    530		*len = 0;
    531	else if (donor_eof < donor_start + *len - 1)
    532		*len = donor_eof - donor_start;
    533	if (!*len) {
    534		ext4_debug("ext4 move extent: len should not be 0 "
    535			"[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
    536			donor_inode->i_ino);
    537		return -EINVAL;
    538	}
    539
    540	return 0;
    541}
    542
    543/**
    544 * ext4_move_extents - Exchange the specified range of a file
    545 *
    546 * @o_filp:		file structure of the original file
    547 * @d_filp:		file structure of the donor file
    548 * @orig_blk:		start offset in block for orig
    549 * @donor_blk:		start offset in block for donor
    550 * @len:		the number of blocks to be moved
    551 * @moved_len:		moved block length
    552 *
    553 * This function returns 0 and moved block length is set in moved_len
    554 * if succeed, otherwise returns error value.
    555 *
    556 */
    557int
    558ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
    559		  __u64 donor_blk, __u64 len, __u64 *moved_len)
    560{
    561	struct inode *orig_inode = file_inode(o_filp);
    562	struct inode *donor_inode = file_inode(d_filp);
    563	struct ext4_ext_path *path = NULL;
    564	int blocks_per_page = PAGE_SIZE >> orig_inode->i_blkbits;
    565	ext4_lblk_t o_end, o_start = orig_blk;
    566	ext4_lblk_t d_start = donor_blk;
    567	int ret;
    568
    569	if (orig_inode->i_sb != donor_inode->i_sb) {
    570		ext4_debug("ext4 move extent: The argument files "
    571			"should be in same FS [ino:orig %lu, donor %lu]\n",
    572			orig_inode->i_ino, donor_inode->i_ino);
    573		return -EINVAL;
    574	}
    575
    576	/* orig and donor should be different inodes */
    577	if (orig_inode == donor_inode) {
    578		ext4_debug("ext4 move extent: The argument files should not "
    579			"be same inode [ino:orig %lu, donor %lu]\n",
    580			orig_inode->i_ino, donor_inode->i_ino);
    581		return -EINVAL;
    582	}
    583
    584	/* Regular file check */
    585	if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
    586		ext4_debug("ext4 move extent: The argument files should be "
    587			"regular file [ino:orig %lu, donor %lu]\n",
    588			orig_inode->i_ino, donor_inode->i_ino);
    589		return -EINVAL;
    590	}
    591
    592	/* TODO: it's not obvious how to swap blocks for inodes with full
    593	   journaling enabled */
    594	if (ext4_should_journal_data(orig_inode) ||
    595	    ext4_should_journal_data(donor_inode)) {
    596		ext4_msg(orig_inode->i_sb, KERN_ERR,
    597			 "Online defrag not supported with data journaling");
    598		return -EOPNOTSUPP;
    599	}
    600
    601	if (IS_ENCRYPTED(orig_inode) || IS_ENCRYPTED(donor_inode)) {
    602		ext4_msg(orig_inode->i_sb, KERN_ERR,
    603			 "Online defrag not supported for encrypted files");
    604		return -EOPNOTSUPP;
    605	}
    606
    607	/* Protect orig and donor inodes against a truncate */
    608	lock_two_nondirectories(orig_inode, donor_inode);
    609
    610	/* Wait for all existing dio workers */
    611	inode_dio_wait(orig_inode);
    612	inode_dio_wait(donor_inode);
    613
    614	/* Protect extent tree against block allocations via delalloc */
    615	ext4_double_down_write_data_sem(orig_inode, donor_inode);
    616	/* Check the filesystem environment whether move_extent can be done */
    617	ret = mext_check_arguments(orig_inode, donor_inode, orig_blk,
    618				    donor_blk, &len);
    619	if (ret)
    620		goto out;
    621	o_end = o_start + len;
    622
    623	while (o_start < o_end) {
    624		struct ext4_extent *ex;
    625		ext4_lblk_t cur_blk, next_blk;
    626		pgoff_t orig_page_index, donor_page_index;
    627		int offset_in_page;
    628		int unwritten, cur_len;
    629
    630		ret = get_ext_path(orig_inode, o_start, &path);
    631		if (ret)
    632			goto out;
    633		ex = path[path->p_depth].p_ext;
    634		next_blk = ext4_ext_next_allocated_block(path);
    635		cur_blk = le32_to_cpu(ex->ee_block);
    636		cur_len = ext4_ext_get_actual_len(ex);
    637		/* Check hole before the start pos */
    638		if (cur_blk + cur_len - 1 < o_start) {
    639			if (next_blk == EXT_MAX_BLOCKS) {
    640				ret = -ENODATA;
    641				goto out;
    642			}
    643			d_start += next_blk - o_start;
    644			o_start = next_blk;
    645			continue;
    646		/* Check hole after the start pos */
    647		} else if (cur_blk > o_start) {
    648			/* Skip hole */
    649			d_start += cur_blk - o_start;
    650			o_start = cur_blk;
    651			/* Extent inside requested range ?*/
    652			if (cur_blk >= o_end)
    653				goto out;
    654		} else { /* in_range(o_start, o_blk, o_len) */
    655			cur_len += cur_blk - o_start;
    656		}
    657		unwritten = ext4_ext_is_unwritten(ex);
    658		if (o_end - o_start < cur_len)
    659			cur_len = o_end - o_start;
    660
    661		orig_page_index = o_start >> (PAGE_SHIFT -
    662					       orig_inode->i_blkbits);
    663		donor_page_index = d_start >> (PAGE_SHIFT -
    664					       donor_inode->i_blkbits);
    665		offset_in_page = o_start % blocks_per_page;
    666		if (cur_len > blocks_per_page- offset_in_page)
    667			cur_len = blocks_per_page - offset_in_page;
    668		/*
    669		 * Up semaphore to avoid following problems:
    670		 * a. transaction deadlock among ext4_journal_start,
    671		 *    ->write_begin via pagefault, and jbd2_journal_commit
    672		 * b. racing with ->read_folio, ->write_begin, and
    673		 *    ext4_get_block in move_extent_per_page
    674		 */
    675		ext4_double_up_write_data_sem(orig_inode, donor_inode);
    676		/* Swap original branches with new branches */
    677		move_extent_per_page(o_filp, donor_inode,
    678				     orig_page_index, donor_page_index,
    679				     offset_in_page, cur_len,
    680				     unwritten, &ret);
    681		ext4_double_down_write_data_sem(orig_inode, donor_inode);
    682		if (ret < 0)
    683			break;
    684		o_start += cur_len;
    685		d_start += cur_len;
    686	}
    687	*moved_len = o_start - orig_blk;
    688	if (*moved_len > len)
    689		*moved_len = len;
    690
    691out:
    692	if (*moved_len) {
    693		ext4_discard_preallocations(orig_inode, 0);
    694		ext4_discard_preallocations(donor_inode, 0);
    695	}
    696
    697	ext4_ext_drop_refs(path);
    698	kfree(path);
    699	ext4_double_up_write_data_sem(orig_inode, donor_inode);
    700	unlock_two_nondirectories(orig_inode, donor_inode);
    701
    702	return ret;
    703}