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move_extent.c
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move_extent.c
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/*
* Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
* Written by Takashi Sato <[email protected]>
* Akira Fujita <[email protected]>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2.1 of the GNU Lesser General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/fs.h>
#include <linux/quotaops.h>
#include <linux/slab.h>
#include "ext4_jbd2.h"
#include "ext4_extents.h"
#include "ext4.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_ext_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 **path)
{
int ret = 0;
*path = ext4_ext_find_extent(inode, lblock, *path);
if (IS_ERR(*path)) {
ret = PTR_ERR(*path);
*path = NULL;
} else if ((*path)[ext_depth(inode)].p_ext == NULL)
ret = -ENODATA;
return ret;
}
/**
* copy_extent_status - Copy the extent's initialization status
*
* @src: an extent for getting initialize status
* @dest: an extent to be set the status
*/
static void
copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
{
if (ext4_ext_is_uninitialized(src))
ext4_ext_mark_uninitialized(dest);
else
dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
}
/**
* mext_next_extent - Search for the next extent and set it to "extent"
*
* @inode: inode which is searched
* @path: this will obtain data for the next extent
* @extent: pointer to the next extent we have just gotten
*
* Search the next extent in the array of ext4_ext_path structure (@path)
* and set it to ext4_extent structure (@extent). In addition, the member of
* @path (->p_ext) also points the next extent. Return 0 on success, 1 if
* ext4_ext_path structure refers to the last extent, or a negative error
* value on failure.
*/
static int
mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
struct ext4_extent **extent)
{
struct ext4_extent_header *eh;
int ppos, leaf_ppos = path->p_depth;
ppos = leaf_ppos;
if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
/* leaf block */
*extent = ++path[ppos].p_ext;
path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
return 0;
}
while (--ppos >= 0) {
if (EXT_LAST_INDEX(path[ppos].p_hdr) >
path[ppos].p_idx) {
int cur_ppos = ppos;
/* index block */
path[ppos].p_idx++;
path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
if (path[ppos+1].p_bh)
brelse(path[ppos+1].p_bh);
path[ppos+1].p_bh =
sb_bread(inode->i_sb, path[ppos].p_block);
if (!path[ppos+1].p_bh)
return -EIO;
path[ppos+1].p_hdr =
ext_block_hdr(path[ppos+1].p_bh);
/* Halfway index block */
while (++cur_ppos < leaf_ppos) {
path[cur_ppos].p_idx =
EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
path[cur_ppos].p_block =
ext4_idx_pblock(path[cur_ppos].p_idx);
if (path[cur_ppos+1].p_bh)
brelse(path[cur_ppos+1].p_bh);
path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
path[cur_ppos].p_block);
if (!path[cur_ppos+1].p_bh)
return -EIO;
path[cur_ppos+1].p_hdr =
ext_block_hdr(path[cur_ppos+1].p_bh);
}
path[leaf_ppos].p_ext = *extent = NULL;
eh = path[leaf_ppos].p_hdr;
if (le16_to_cpu(eh->eh_entries) == 0)
/* empty leaf is found */
return -ENODATA;
/* leaf block */
path[leaf_ppos].p_ext = *extent =
EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
path[leaf_ppos].p_block =
ext4_ext_pblock(path[leaf_ppos].p_ext);
return 0;
}
}
/* We found the last extent */
return 1;
}
/**
* mext_check_null_inode - NULL check for two inodes
*
* If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
*/
static int
mext_check_null_inode(struct inode *inode1, struct inode *inode2,
const char *function, unsigned int line)
{
int ret = 0;
if (inode1 == NULL) {
__ext4_error(inode2->i_sb, function, line,
"Both inodes should not be NULL: "
"inode1 NULL inode2 %lu", inode2->i_ino);
ret = -EIO;
} else if (inode2 == NULL) {
__ext4_error(inode1->i_sb, function, line,
"Both inodes should not be NULL: "
"inode1 %lu inode2 NULL", inode1->i_ino);
ret = -EIO;
}
return ret;
}
/**
* double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem
*
* @orig_inode: original inode structure
* @donor_inode: donor inode structure
* Acquire write lock of i_data_sem of the two inodes (orig and donor) by
* i_ino order.
*/
static void
double_down_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
{
struct inode *first = orig_inode, *second = donor_inode;
/*
* Use the inode number to provide the stable locking order instead
* of its address, because the C language doesn't guarantee you can
* compare pointers that don't come from the same array.
*/
if (donor_inode->i_ino < orig_inode->i_ino) {
first = donor_inode;
second = orig_inode;
}
down_write(&EXT4_I(first)->i_data_sem);
down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
}
/**
* 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).
*/
static void
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_insert_across_blocks - Insert extents across leaf block
*
* @handle: journal handle
* @orig_inode: original inode
* @o_start: first original extent to be changed
* @o_end: last original extent to be changed
* @start_ext: first new extent to be inserted
* @new_ext: middle of new extent to be inserted
* @end_ext: last new extent to be inserted
*
* Allocate a new leaf block and insert extents into it. Return 0 on success,
* or a negative error value on failure.
*/
static int
mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
struct ext4_extent *o_start, struct ext4_extent *o_end,
struct ext4_extent *start_ext, struct ext4_extent *new_ext,
struct ext4_extent *end_ext)
{
struct ext4_ext_path *orig_path = NULL;
ext4_lblk_t eblock = 0;
int new_flag = 0;
int end_flag = 0;
int err = 0;
if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
if (o_start == o_end) {
/* start_ext new_ext end_ext
* donor |---------|-----------|--------|
* orig |------------------------------|
*/
end_flag = 1;
} else {
/* start_ext new_ext end_ext
* donor |---------|----------|---------|
* orig |---------------|--------------|
*/
o_end->ee_block = end_ext->ee_block;
o_end->ee_len = end_ext->ee_len;
ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
}
o_start->ee_len = start_ext->ee_len;
eblock = le32_to_cpu(start_ext->ee_block);
new_flag = 1;
} else if (start_ext->ee_len && new_ext->ee_len &&
!end_ext->ee_len && o_start == o_end) {
/* start_ext new_ext
* donor |--------------|---------------|
* orig |------------------------------|
*/
o_start->ee_len = start_ext->ee_len;
eblock = le32_to_cpu(start_ext->ee_block);
new_flag = 1;
} else if (!start_ext->ee_len && new_ext->ee_len &&
end_ext->ee_len && o_start == o_end) {
/* new_ext end_ext
* donor |--------------|---------------|
* orig |------------------------------|
*/
o_end->ee_block = end_ext->ee_block;
o_end->ee_len = end_ext->ee_len;
ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
/*
* Set 0 to the extent block if new_ext was
* the first block.
*/
if (new_ext->ee_block)
eblock = le32_to_cpu(new_ext->ee_block);
new_flag = 1;
} else {
ext4_debug("ext4 move extent: Unexpected insert case\n");
return -EIO;
}
if (new_flag) {
err = get_ext_path(orig_inode, eblock, &orig_path);
if (err)
goto out;
if (ext4_ext_insert_extent(handle, orig_inode,
orig_path, new_ext, 0))
goto out;
}
if (end_flag) {
err = get_ext_path(orig_inode,
le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
if (err)
goto out;
if (ext4_ext_insert_extent(handle, orig_inode,
orig_path, end_ext, 0))
goto out;
}
out:
if (orig_path) {
ext4_ext_drop_refs(orig_path);
kfree(orig_path);
}
return err;
}
/**
* mext_insert_inside_block - Insert new extent to the extent block
*
* @o_start: first original extent to be moved
* @o_end: last original extent to be moved
* @start_ext: first new extent to be inserted
* @new_ext: middle of new extent to be inserted
* @end_ext: last new extent to be inserted
* @eh: extent header of target leaf block
* @range_to_move: used to decide how to insert extent
*
* Insert extents into the leaf block. The extent (@o_start) is overwritten
* by inserted extents.
*/
static void
mext_insert_inside_block(struct ext4_extent *o_start,
struct ext4_extent *o_end,
struct ext4_extent *start_ext,
struct ext4_extent *new_ext,
struct ext4_extent *end_ext,
struct ext4_extent_header *eh,
int range_to_move)
{
int i = 0;
unsigned long len;
/* Move the existing extents */
if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
(unsigned long)(o_end + 1);
memmove(o_end + 1 + range_to_move, o_end + 1, len);
}
/* Insert start entry */
if (start_ext->ee_len)
o_start[i++].ee_len = start_ext->ee_len;
/* Insert new entry */
if (new_ext->ee_len) {
o_start[i] = *new_ext;
ext4_ext_store_pblock(&o_start[i++], ext4_ext_pblock(new_ext));
}
/* Insert end entry */
if (end_ext->ee_len)
o_start[i] = *end_ext;
/* Increment the total entries counter on the extent block */
le16_add_cpu(&eh->eh_entries, range_to_move);
}
/**
* mext_insert_extents - Insert new extent
*
* @handle: journal handle
* @orig_inode: original inode
* @orig_path: path indicates first extent to be changed
* @o_start: first original extent to be changed
* @o_end: last original extent to be changed
* @start_ext: first new extent to be inserted
* @new_ext: middle of new extent to be inserted
* @end_ext: last new extent to be inserted
*
* Call the function to insert extents. If we cannot add more extents into
* the leaf block, we call mext_insert_across_blocks() to create a
* new leaf block. Otherwise call mext_insert_inside_block(). Return 0
* on success, or a negative error value on failure.
*/
static int
mext_insert_extents(handle_t *handle, struct inode *orig_inode,
struct ext4_ext_path *orig_path,
struct ext4_extent *o_start,
struct ext4_extent *o_end,
struct ext4_extent *start_ext,
struct ext4_extent *new_ext,
struct ext4_extent *end_ext)
{
struct ext4_extent_header *eh;
unsigned long need_slots, slots_range;
int range_to_move, depth, ret;
/*
* The extents need to be inserted
* start_extent + new_extent + end_extent.
*/
need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
(new_ext->ee_len ? 1 : 0);
/* The number of slots between start and end */
slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
/ sizeof(struct ext4_extent);
/* Range to move the end of extent */
range_to_move = need_slots - slots_range;
depth = orig_path->p_depth;
orig_path += depth;
eh = orig_path->p_hdr;
if (depth) {
/* Register to journal */
ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
if (ret)
return ret;
}
/* Expansion */
if (range_to_move > 0 &&
(range_to_move > le16_to_cpu(eh->eh_max)
- le16_to_cpu(eh->eh_entries))) {
ret = mext_insert_across_blocks(handle, orig_inode, o_start,
o_end, start_ext, new_ext, end_ext);
if (ret < 0)
return ret;
} else
mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
end_ext, eh, range_to_move);
if (depth) {
ret = ext4_handle_dirty_metadata(handle, orig_inode,
orig_path->p_bh);
if (ret)
return ret;
} else {
ret = ext4_mark_inode_dirty(handle, orig_inode);
if (ret < 0)
return ret;
}
return 0;
}
/**
* mext_leaf_block - Move one leaf extent block into the inode.
*
* @handle: journal handle
* @orig_inode: original inode
* @orig_path: path indicates first extent to be changed
* @dext: donor extent
* @from: start offset on the target file
*
* In order to insert extents into the leaf block, we must divide the extent
* in the leaf block into three extents. The one is located to be inserted
* extents, and the others are located around it.
*
* Therefore, this function creates structures to save extents of the leaf
* block, and inserts extents by calling mext_insert_extents() with
* created extents. Return 0 on success, or a negative error value on failure.
*/
static int
mext_leaf_block(handle_t *handle, struct inode *orig_inode,
struct ext4_ext_path *orig_path, struct ext4_extent *dext,
ext4_lblk_t *from)
{
struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
struct ext4_extent new_ext, start_ext, end_ext;
ext4_lblk_t new_ext_end;
int oext_alen, new_ext_alen, end_ext_alen;
int depth = ext_depth(orig_inode);
int ret;
start_ext.ee_block = end_ext.ee_block = 0;
o_start = o_end = oext = orig_path[depth].p_ext;
oext_alen = ext4_ext_get_actual_len(oext);
start_ext.ee_len = end_ext.ee_len = 0;
new_ext.ee_block = cpu_to_le32(*from);
ext4_ext_store_pblock(&new_ext, ext4_ext_pblock(dext));
new_ext.ee_len = dext->ee_len;
new_ext_alen = ext4_ext_get_actual_len(&new_ext);
new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
/*
* Case: original extent is first
* oext |--------|
* new_ext |--|
* start_ext |--|
*/
if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
le32_to_cpu(new_ext.ee_block) <
le32_to_cpu(oext->ee_block) + oext_alen) {
start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
le32_to_cpu(oext->ee_block));
start_ext.ee_block = oext->ee_block;
copy_extent_status(oext, &start_ext);
} else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
prev_ext = oext - 1;
/*
* We can merge new_ext into previous extent,
* if these are contiguous and same extent type.
*/
if (ext4_can_extents_be_merged(orig_inode, prev_ext,
&new_ext)) {
o_start = prev_ext;
start_ext.ee_len = cpu_to_le16(
ext4_ext_get_actual_len(prev_ext) +
new_ext_alen);
start_ext.ee_block = oext->ee_block;
copy_extent_status(prev_ext, &start_ext);
new_ext.ee_len = 0;
}
}
/*
* Case: new_ext_end must be less than oext
* oext |-----------|
* new_ext |-------|
*/
if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
EXT4_ERROR_INODE(orig_inode,
"new_ext_end(%u) should be less than or equal to "
"oext->ee_block(%u) + oext_alen(%d) - 1",
new_ext_end, le32_to_cpu(oext->ee_block),
oext_alen);
ret = -EIO;
goto out;
}
/*
* Case: new_ext is smaller than original extent
* oext |---------------|
* new_ext |-----------|
* end_ext |---|
*/
if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
end_ext.ee_len =
cpu_to_le16(le32_to_cpu(oext->ee_block) +
oext_alen - 1 - new_ext_end);
copy_extent_status(oext, &end_ext);
end_ext_alen = ext4_ext_get_actual_len(&end_ext);
ext4_ext_store_pblock(&end_ext,
(ext4_ext_pblock(o_end) + oext_alen - end_ext_alen));
end_ext.ee_block =
cpu_to_le32(le32_to_cpu(o_end->ee_block) +
oext_alen - end_ext_alen);
}
ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
o_end, &start_ext, &new_ext, &end_ext);
out:
return ret;
}
/**
* mext_calc_swap_extents - Calculate extents for extent swapping.
*
* @tmp_dext: the extent that will belong to the original inode
* @tmp_oext: the extent that will belong to the donor inode
* @orig_off: block offset of original inode
* @donor_off: block offset of donor inode
* @max_count: the maximum length of extents
*
* Return 0 on success, or a negative error value on failure.
*/
static int
mext_calc_swap_extents(struct ext4_extent *tmp_dext,
struct ext4_extent *tmp_oext,
ext4_lblk_t orig_off, ext4_lblk_t donor_off,
ext4_lblk_t max_count)
{
ext4_lblk_t diff, orig_diff;
struct ext4_extent dext_old, oext_old;
BUG_ON(orig_off != donor_off);
/* original and donor extents have to cover the same block offset */
if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
le32_to_cpu(tmp_oext->ee_block) +
ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
return -ENODATA;
if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
le32_to_cpu(tmp_dext->ee_block) +
ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
return -ENODATA;
dext_old = *tmp_dext;
oext_old = *tmp_oext;
/* When tmp_dext is too large, pick up the target range. */
diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
ext4_ext_store_pblock(tmp_dext, ext4_ext_pblock(tmp_dext) + diff);
tmp_dext->ee_block =
cpu_to_le32(le32_to_cpu(tmp_dext->ee_block) + diff);
tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_dext->ee_len) - diff);
if (max_count < ext4_ext_get_actual_len(tmp_dext))
tmp_dext->ee_len = cpu_to_le16(max_count);
orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
/* Adjust extent length if donor extent is larger than orig */
if (ext4_ext_get_actual_len(tmp_dext) >
ext4_ext_get_actual_len(tmp_oext) - orig_diff)
tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
orig_diff);
tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
copy_extent_status(&oext_old, tmp_dext);
copy_extent_status(&dext_old, tmp_oext);
return 0;
}
/**
* mext_replace_branches - Replace original extents with new extents
*
* @handle: journal handle
* @orig_inode: original inode
* @donor_inode: donor inode
* @from: block offset of orig_inode
* @count: block count to be replaced
* @err: pointer to save return value
*
* Replace original inode extents and donor inode extents page by page.
* We implement this replacement in the following three steps:
* 1. Save the block information of original and donor inodes into
* dummy extents.
* 2. Change the block information of original inode to point at the
* donor inode blocks.
* 3. Change the block information of donor inode to point at the saved
* original inode blocks in the dummy extents.
*
* Return replaced block count.
*/
static int
mext_replace_branches(handle_t *handle, struct inode *orig_inode,
struct inode *donor_inode, ext4_lblk_t from,
ext4_lblk_t count, int *err)
{
struct ext4_ext_path *orig_path = NULL;
struct ext4_ext_path *donor_path = NULL;
struct ext4_extent *oext, *dext;
struct ext4_extent tmp_dext, tmp_oext;
ext4_lblk_t orig_off = from, donor_off = from;
int depth;
int replaced_count = 0;
int dext_alen;
/* Protect extent trees against block allocations via delalloc */
double_down_write_data_sem(orig_inode, donor_inode);
/* Get the original extent for the block "orig_off" */
*err = get_ext_path(orig_inode, orig_off, &orig_path);
if (*err)
goto out;
/* Get the donor extent for the head */
*err = get_ext_path(donor_inode, donor_off, &donor_path);
if (*err)
goto out;
depth = ext_depth(orig_inode);
oext = orig_path[depth].p_ext;
tmp_oext = *oext;
depth = ext_depth(donor_inode);
dext = donor_path[depth].p_ext;
tmp_dext = *dext;
*err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
donor_off, count);
if (*err)
goto out;
/* Loop for the donor extents */
while (1) {
/* The extent for donor must be found. */
if (!dext) {
EXT4_ERROR_INODE(donor_inode,
"The extent for donor must be found");
*err = -EIO;
goto out;
} else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
EXT4_ERROR_INODE(donor_inode,
"Donor offset(%u) and the first block of donor "
"extent(%u) should be equal",
donor_off,
le32_to_cpu(tmp_dext.ee_block));
*err = -EIO;
goto out;
}
/* Set donor extent to orig extent */
*err = mext_leaf_block(handle, orig_inode,
orig_path, &tmp_dext, &orig_off);
if (*err)
goto out;
/* Set orig extent to donor extent */
*err = mext_leaf_block(handle, donor_inode,
donor_path, &tmp_oext, &donor_off);
if (*err)
goto out;
dext_alen = ext4_ext_get_actual_len(&tmp_dext);
replaced_count += dext_alen;
donor_off += dext_alen;
orig_off += dext_alen;
/* Already moved the expected blocks */
if (replaced_count >= count)
break;
if (orig_path)
ext4_ext_drop_refs(orig_path);
*err = get_ext_path(orig_inode, orig_off, &orig_path);
if (*err)
goto out;
depth = ext_depth(orig_inode);
oext = orig_path[depth].p_ext;
tmp_oext = *oext;
if (donor_path)
ext4_ext_drop_refs(donor_path);
*err = get_ext_path(donor_inode, donor_off, &donor_path);
if (*err)
goto out;
depth = ext_depth(donor_inode);
dext = donor_path[depth].p_ext;
tmp_dext = *dext;
*err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
donor_off, count - replaced_count);
if (*err)
goto out;
}
out:
if (orig_path) {
ext4_ext_drop_refs(orig_path);
kfree(orig_path);
}
if (donor_path) {
ext4_ext_drop_refs(donor_path);
kfree(donor_path);
}
ext4_ext_invalidate_cache(orig_inode);
ext4_ext_invalidate_cache(donor_inode);
double_up_write_data_sem(orig_inode, donor_inode);
return replaced_count;
}
/**
* 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
* @data_offset_in_page: block index where data swapping starts
* @block_len_in_page: the number of blocks to be swapped
* @uninit: orig extent is uninitialized 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 mext_replace_branches().
* 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, int data_offset_in_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;
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 replaced_count = 0;
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.
*/
jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
handle = ext4_journal_start(orig_inode, jblocks);
if (IS_ERR(handle)) {
*err = PTR_ERR(handle);
return 0;
}
if (segment_eq(get_fs(), KERNEL_DS))
w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
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 */
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 = a_ops->write_begin(o_filp, mapping, offs, data_size, w_flags,
&page, &fsdata);
if (unlikely(*err < 0))
goto out;
if (!PageUptodate(page)) {
mapping->a_ops->readpage(o_filp, page);
lock_page(page);
}
/*
* 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) {
if (replaced_count) {
block_len_in_page = replaced_count;
replaced_size =
block_len_in_page << orig_inode->i_blkbits;
} else
goto out;
}
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:
ext4_journal_stop(handle);
if (err2)
*err = err2;
return replaced_count;
}
/**
* 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)
{
ext4_lblk_t orig_blocks, donor_blocks;
unsigned int blkbits = orig_inode->i_blkbits;
unsigned int 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 -EINVAL;
}
/* Files should be in the same ext4 FS */
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;
}
/* 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 != donor_start) {
ext4_debug("ext4 move extent: orig and donor's start "
"offset are not same [ino:orig %lu, donor %lu]\n",