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ext4: add punching hole support for non-extent-mapped files
This patch add supports for indirect file support punching hole.  It
is almost the same as ext4_ext_punch_hole.  First, we invalidate all
pages between this hole, and then we try to deallocate all blocks of
this hole.

A recursive function is used to handle deallocation of blocks.  In
this function, it iterates over the entries in inode's i_blocks or
indirect blocks, and try to free the block for each one of them.

After applying this patch, xfstest raspberrypi#255 will not pass w/o extent because
indirect-based file doesn't support unwritten extents.

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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gnehzuil authored and tytso committed Jan 28, 2013
1 parent 03dafb5 commit 8bad6fc
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Showing 4 changed files with 250 additions and 11 deletions.
1 change: 1 addition & 0 deletions fs/ext4/ext4.h
Expand Up @@ -2103,6 +2103,7 @@ extern ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
extern int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock);
extern int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk);
extern void ext4_ind_truncate(struct inode *inode);
extern int ext4_ind_punch_hole(struct file *file, loff_t offset, loff_t length);

/* ioctl.c */
extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
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14 changes: 7 additions & 7 deletions fs/ext4/extents.c
Expand Up @@ -4400,13 +4400,6 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
struct ext4_map_blocks map;
unsigned int credits, blkbits = inode->i_blkbits;

/*
* currently supporting (pre)allocate mode for extent-based
* files _only_
*/
if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
return -EOPNOTSUPP;

/* Return error if mode is not supported */
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
return -EOPNOTSUPP;
Expand All @@ -4418,6 +4411,13 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
if (ret)
return ret;

/*
* currently supporting (pre)allocate mode for extent-based
* files _only_
*/
if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
return -EOPNOTSUPP;

trace_ext4_fallocate_enter(inode, offset, len, mode);
map.m_lblk = offset >> blkbits;
/*
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240 changes: 240 additions & 0 deletions fs/ext4/indirect.c
Expand Up @@ -1518,3 +1518,243 @@ void ext4_ind_truncate(struct inode *inode)
trace_ext4_truncate_exit(inode);
}

static int free_hole_blocks(handle_t *handle, struct inode *inode,
struct buffer_head *parent_bh, __le32 *i_data,
int level, ext4_lblk_t first,
ext4_lblk_t count, int max)
{
struct buffer_head *bh = NULL;
int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
int ret = 0;
int i, inc;
ext4_lblk_t offset;
__le32 blk;

inc = 1 << ((EXT4_BLOCK_SIZE_BITS(inode->i_sb) - 2) * level);
for (i = 0, offset = 0; i < max; i++, i_data++, offset += inc) {
if (offset >= count + first)
break;
if (*i_data == 0 || (offset + inc) <= first)
continue;
blk = *i_data;
if (level > 0) {
ext4_lblk_t first2;
bh = sb_bread(inode->i_sb, blk);
if (!bh) {
EXT4_ERROR_INODE_BLOCK(inode, blk,
"Read failure");
return -EIO;
}
first2 = (first > offset) ? first - offset : 0;
ret = free_hole_blocks(handle, inode, bh,
(__le32 *)bh->b_data, level - 1,
first2, count - offset,
inode->i_sb->s_blocksize >> 2);
if (ret) {
brelse(bh);
goto err;
}
}
if (level == 0 ||
(bh && all_zeroes((__le32 *)bh->b_data,
(__le32 *)bh->b_data + addr_per_block))) {
ext4_free_data(handle, inode, parent_bh, &blk, &blk+1);
*i_data = 0;
}
brelse(bh);
bh = NULL;
}

err:
return ret;
}

static int ext4_free_hole_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t first, ext4_lblk_t stop)
{
int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
int level, ret = 0;
int num = EXT4_NDIR_BLOCKS;
ext4_lblk_t count, max = EXT4_NDIR_BLOCKS;
__le32 *i_data = EXT4_I(inode)->i_data;

count = stop - first;
for (level = 0; level < 4; level++, max *= addr_per_block) {
if (first < max) {
ret = free_hole_blocks(handle, inode, NULL, i_data,
level, first, count, num);
if (ret)
goto err;
if (count > max - first)
count -= max - first;
else
break;
first = 0;
} else {
first -= max;
}
i_data += num;
if (level == 0) {
num = 1;
max = 1;
}
}

err:
return ret;
}

int ext4_ind_punch_hole(struct file *file, loff_t offset, loff_t length)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct super_block *sb = inode->i_sb;
ext4_lblk_t first_block, stop_block;
struct address_space *mapping = inode->i_mapping;
handle_t *handle = NULL;
loff_t first_page, last_page, page_len;
loff_t first_page_offset, last_page_offset;
int err = 0;

/*
* Write out all dirty pages to avoid race conditions
* Then release them.
*/
if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
err = filemap_write_and_wait_range(mapping,
offset, offset + length - 1);
if (err)
return err;
}

mutex_lock(&inode->i_mutex);
/* It's not possible punch hole on append only file */
if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
err = -EPERM;
goto out_mutex;
}
if (IS_SWAPFILE(inode)) {
err = -ETXTBSY;
goto out_mutex;
}

/* No need to punch hole beyond i_size */
if (offset >= inode->i_size)
goto out_mutex;

/*
* If the hole extents beyond i_size, set the hole
* to end after the page that contains i_size
*/
if (offset + length > inode->i_size) {
length = inode->i_size +
PAGE_CACHE_SIZE - (inode->i_size & (PAGE_CACHE_SIZE - 1)) -
offset;
}

first_page = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
last_page = (offset + length) >> PAGE_CACHE_SHIFT;

first_page_offset = first_page << PAGE_CACHE_SHIFT;
last_page_offset = last_page << PAGE_CACHE_SHIFT;

/* Now release the pages */
if (last_page_offset > first_page_offset) {
truncate_pagecache_range(inode, first_page_offset,
last_page_offset - 1);
}

/* Wait all existing dio works, newcomers will block on i_mutex */
inode_dio_wait(inode);

handle = start_transaction(inode);
if (IS_ERR(handle))
goto out_mutex;

/*
* Now we need to zero out the non-page-aligned data in the
* pages at the start and tail of the hole, and unmap the buffer
* heads for the block aligned regions of the page that were
* completely zerod.
*/
if (first_page > last_page) {
/*
* If the file space being truncated is contained within a page
* just zero out and unmap the middle of that page
*/
err = ext4_discard_partial_page_buffers(handle,
mapping, offset, length, 0);
if (err)
goto out;
} else {
/*
* Zero out and unmap the paritial page that contains
* the start of the hole
*/
page_len = first_page_offset - offset;
if (page_len > 0) {
err = ext4_discard_partial_page_buffers(handle, mapping,
offset, page_len, 0);
if (err)
goto out;
}

/*
* Zero out and unmap the partial page that contains
* the end of the hole
*/
page_len = offset + length - last_page_offset;
if (page_len > 0) {
err = ext4_discard_partial_page_buffers(handle, mapping,
last_page_offset, page_len, 0);
if (err)
goto out;
}
}

/*
* If i_size contained in the last page, we need to
* unmap and zero the paritial page after i_size
*/
if (inode->i_size >> PAGE_CACHE_SHIFT == last_page &&
inode->i_size % PAGE_CACHE_SIZE != 0) {
page_len = PAGE_CACHE_SIZE -
(inode->i_size & (PAGE_CACHE_SIZE - 1));
if (page_len > 0) {
err = ext4_discard_partial_page_buffers(handle,
mapping, inode->i_size, page_len, 0);
if (err)
goto out;
}
}

first_block = (offset + sb->s_blocksize - 1) >>
EXT4_BLOCK_SIZE_BITS(sb);
stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);

if (first_block >= stop_block)
goto out;

down_write(&EXT4_I(inode)->i_data_sem);
ext4_discard_preallocations(inode);

err = ext4_es_remove_extent(inode, first_block,
stop_block - first_block);
err = ext4_free_hole_blocks(handle, inode, first_block, stop_block);

ext4_discard_preallocations(inode);

if (IS_SYNC(inode))
ext4_handle_sync(handle);

up_write(&EXT4_I(inode)->i_data_sem);

out:
inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
ext4_mark_inode_dirty(handle, inode);
ext4_journal_stop(handle);

out_mutex:
mutex_unlock(&inode->i_mutex);

return err;
}
6 changes: 2 additions & 4 deletions fs/ext4/inode.c
Expand Up @@ -3557,10 +3557,8 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
if (!S_ISREG(inode->i_mode))
return -EOPNOTSUPP;

if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
/* TODO: Add support for non extent hole punching */
return -EOPNOTSUPP;
}
if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
return ext4_ind_punch_hole(file, offset, length);

if (EXT4_SB(inode->i_sb)->s_cluster_ratio > 1) {
/* TODO: Add support for bigalloc file systems */
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