On Sat, 2011-05-07 at 16:54 -0700, Allison Henderson wrote:
> This patch adds new routines: "ext4_punch_hole" "ext4_ext_punch_hole"
> and "ext4_ext_check_cache"
>
> fallocate has been modified to call ext4_punch_hole when the punch hole
> flag is passed. At the moment, we only support punching holes in
> extents, so this routine is pretty much a wrapper for the ext4_ext_punch_hole
> routine.
>
> The ext4_ext_punch_hole routine first completes all
> outstanding writes with the associated pages, and then releases
> them. The unblock aligned data is zeroed, and all blocks in
> between are punched out.
>
> The ext4_ext_check_cache routine is very similar to
> ext4_ext_in_cache except it accepts a ext4_ext_cache
> parameter instead of a ext4_extent parameter. This routine
> is used by ext4_ext_punch_hole to check and see if a block
> in a hole that has been cached. The ext4_ext_cache parameter
> is necessary because the members ext4_extent structure are
> not large enough to hold a 32 bit value. The existing
> ext4_ext_in_cache routine has become a wrapper to this
> new function.
>
> Signed-off-by: Allison Henderson <achender@xxxxxxxxxx>
Looks the same as last version. you could add my reviewed-by
Reviewed-by: Mingming Cao <cmm@xxxxxxxxxx>
> ---
> :100644 100644 95efb4e... a1137cd... M fs/ext4/ext4.h
> :100644 100644 9c3c008... 21cb680... M fs/ext4/extents.c
> :100644 100644 8ce382d... a8c23ec... M fs/ext4/inode.c
> fs/ext4/ext4.h | 3 +
> fs/ext4/extents.c | 240 ++++++++++++++++++++++++++++++++++++++++++++++++++---
> fs/ext4/inode.c | 25 ++++++
> 3 files changed, 257 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 95efb4e..a1137cd 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1749,6 +1749,7 @@ extern int ext4_change_inode_journal_flag(struct inode *, int);
> extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *);
> extern int ext4_can_truncate(struct inode *inode);
> extern void ext4_truncate(struct inode *);
> +extern int ext4_punch_hole(struct file *file, loff_t offset, loff_t length);
> extern int ext4_truncate_restart_trans(handle_t *, struct inode *, int nblocks);
> extern void ext4_set_inode_flags(struct inode *);
> extern void ext4_get_inode_flags(struct ext4_inode_info *);
> @@ -2086,6 +2087,8 @@ extern int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks,
> extern int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
> struct ext4_map_blocks *map, int flags);
> extern void ext4_ext_truncate(struct inode *);
> +extern int ext4_ext_punch_hole(struct file *file, loff_t offset,
> + loff_t length);
> extern void ext4_ext_init(struct super_block *);
> extern void ext4_ext_release(struct super_block *);
> extern long ext4_fallocate(struct file *file, int mode, loff_t offset,
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 9c3c008..21cb680 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -2045,12 +2045,23 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
> }
>
> /*
> + * ext4_ext_in_cache()
> + * Checks to see if the given block is in the cache.
> + * If it is, the cached extent is stored in the given
> + * cache extent pointer. If the cached extent is a hole,
> + * this routine should be used instead of
> + * ext4_ext_in_cache if the calling function needs to
> + * know the size of the hole.
> + *
> + * @inode: The files inode
> + * @block: The block to look for in the cache
> + * @ex: Pointer where the cached extent will be stored
> + * if it contains block
> + *
> * Return 0 if cache is invalid; 1 if the cache is valid
> */
> -static int
> -ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
> - struct ext4_extent *ex)
> -{
> +static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
> + struct ext4_ext_cache *ex){
> struct ext4_ext_cache *cex;
> int ret = 0;
>
> @@ -2065,9 +2076,7 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
> goto errout;
>
> if (in_range(block, cex->ec_block, cex->ec_len)) {
> - ex->ee_block = cpu_to_le32(cex->ec_block);
> - ext4_ext_store_pblock(ex, cex->ec_start);
> - ex->ee_len = cpu_to_le16(cex->ec_len);
> + memcpy(ex, cex, sizeof(struct ext4_ext_cache));
> ext_debug("%u cached by %u:%u:%llu\n",
> block,
> cex->ec_block, cex->ec_len, cex->ec_start);
> @@ -2079,6 +2088,37 @@ errout:
> }
>
> /*
> + * ext4_ext_in_cache()
> + * Checks to see if the given block is in the cache.
> + * If it is, the cached extent is stored in the given
> + * extent pointer.
> + *
> + * @inode: The files inode
> + * @block: The block to look for in the cache
> + * @ex: Pointer where the cached extent will be stored
> + * if it contains block
> + *
> + * Return 0 if cache is invalid; 1 if the cache is valid
> + */
> +static int
> +ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
> + struct ext4_extent *ex)
> +{
> + struct ext4_ext_cache cex;
> + int ret = 0;
> +
> + if (ext4_ext_check_cache(inode, block, &cex)) {
> + ex->ee_block = cpu_to_le32(cex.ec_block);
> + ext4_ext_store_pblock(ex, cex.ec_start);
> + ex->ee_len = cpu_to_le16(cex.ec_len);
> + ret = 1;
> + }
> +
> + return ret;
> +}
> +
> +
> +/*
> * ext4_ext_rm_idx:
> * removes index from the index block.
> * It's used in truncate case only, thus all requests are for
> @@ -3740,10 +3780,6 @@ 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;
>
> - /* We only support the FALLOC_FL_KEEP_SIZE mode */
> - if (mode & ~FALLOC_FL_KEEP_SIZE)
> - return -EOPNOTSUPP;
> -
> /*
> * currently supporting (pre)allocate mode for extent-based
> * files _only_
> @@ -3751,6 +3787,13 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> 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;
> +
> + if (mode & FALLOC_FL_PUNCH_HOLE)
> + return ext4_punch_hole(file, offset, len);
> +
> trace_ext4_fallocate_enter(inode, offset, len, mode);
> map.m_lblk = offset >> blkbits;
> /*
> @@ -4132,3 +4175,178 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> return error;
> }
>
> +/*
> + * ext4_ext_punch_hole
> + *
> + * Punches a hole of "length" bytes in a file starting
> + * at byte "offset"
> + *
> + * @inode: The inode of the file to punch a hole in
> + * @offset: The starting byte offset of the hole
> + * @length: The length of the hole
> + *
> + * Returns the number of blocks removed or negative on err
> + */
> +int ext4_ext_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;
> + struct ext4_ext_cache cache_ex;
> + ext4_lblk_t first_block, last_block, num_blocks, iblock, max_blocks;
> + struct address_space *mapping = inode->i_mapping;
> + struct ext4_map_blocks map;
> + handle_t *handle;
> + loff_t first_block_offset, last_block_offset, block_len;
> + loff_t first_page, last_page, first_page_offset, last_page_offset;
> + int ret, credits, blocks_released, err = 0;
> +
> + first_block = (offset + sb->s_blocksize - 1)
> + >> EXT4_BLOCK_SIZE_BITS(sb);
> + last_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
> +
> + first_block_offset = first_block
> + << EXT4_BLOCK_SIZE_BITS(sb);
> + last_block_offset = last_block << EXT4_BLOCK_SIZE_BITS(sb);
> +
> + 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;
> +
> + /*
> + * 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,
> + first_page_offset == 0 ? 0 : first_page_offset-1,
> + last_page_offset);
> +
> + if (err)
> + return err;
> + }
> +
> + /* Now release the pages */
> + if (last_page_offset > first_page_offset) {
> + truncate_inode_pages_range(mapping, first_page_offset,
> + last_page_offset-1);
> + }
> +
> + /* finish any pending end_io work */
> + ext4_flush_completed_IO(inode);
> +
> + credits = ext4_writepage_trans_blocks(inode);
> + handle = ext4_journal_start(inode, credits);
> + if (IS_ERR(handle))
> + return PTR_ERR(handle);
> +
> + err = ext4_orphan_add(handle, inode);
> + if (err)
> + goto out;
> +
> + /*
> + * Now we need to zero out the un block aligned data.
> + * If the file is smaller than a block, just
> + * zero out the middle
> + */
> + if (first_block > last_block)
> + ext4_block_zero_page_range(handle, mapping, offset, length);
> + else {
> + /* zero out the head of the hole before the first block */
> + block_len = first_block_offset - offset;
> + if (block_len > 0)
> + ext4_block_zero_page_range(handle, mapping,
> + offset, block_len);
> +
> + /* zero out the tail of the hole after the last block */
> + block_len = offset + length - last_block_offset;
> + if (block_len > 0) {
> + ext4_block_zero_page_range(handle, mapping,
> + last_block_offset, block_len);
> + }
> + }
> +
> + /* If there are no blocks to remove, return now */
> + if (first_block >= last_block)
> + goto out;
> +
> + down_write(&EXT4_I(inode)->i_data_sem);
> + ext4_ext_invalidate_cache(inode);
> + ext4_discard_preallocations(inode);
> +
> + /*
> + * Loop over all the blocks and identify blocks
> + * that need to be punched out
> + */
> + iblock = first_block;
> + blocks_released = 0;
> + while (iblock < last_block) {
> + max_blocks = last_block - iblock;
> + num_blocks = 1;
> + memset(&map, 0, sizeof(map));
> + map.m_lblk = iblock;
> + map.m_len = max_blocks;
> + ret = ext4_ext_map_blocks(handle, inode, &map,
> + EXT4_GET_BLOCKS_PUNCH_OUT_EXT);
> +
> + if (ret > 0) {
> + blocks_released += ret;
> + num_blocks = ret;
> + } else if (ret == 0) {
> + /*
> + * If map blocks could not find the block,
> + * then it is in a hole. If the hole was
> + * not already cached, then map blocks should
> + * put it in the cache. So we can get the hole
> + * out of the cache
> + */
> + memset(&cache_ex, 0, sizeof(cache_ex));
> + if ((ext4_ext_check_cache(inode, iblock, &cache_ex)) &&
> + !cache_ex.ec_start) {
> +
> + /* The hole is cached */
> + num_blocks = cache_ex.ec_block +
> + cache_ex.ec_len - iblock;
> +
> + } else {
> + /* The block could not be identified */
> + err = -EIO;
> + break;
> + }
> + } else {
> + /* Map blocks error */
> + err = ret;
> + break;
> + }
> +
> + if (num_blocks == 0) {
> + /* This condition should never happen */
> + ext_debug("Block lookup failed");
> + err = -EIO;
> + break;
> + }
> +
> + iblock += num_blocks;
> + }
> +
> + if (blocks_released > 0) {
> + ext4_ext_invalidate_cache(inode);
> + ext4_discard_preallocations(inode);
> + }
> +
> + if (IS_SYNC(inode))
> + ext4_handle_sync(handle);
> +
> + up_write(&EXT4_I(inode)->i_data_sem);
> +
> +out:
> + ext4_orphan_del(handle, inode);
> + inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
> + ext4_mark_inode_dirty(handle, inode);
> + ext4_journal_stop(handle);
> + return err;
> +}
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 8ce382d..a8c23ec 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4421,6 +4421,31 @@ int ext4_can_truncate(struct inode *inode)
> }
>
> /*
> + * ext4_punch_hole: punches a hole in a file by releaseing the blocks
> + * associated with the given offset and length
> + *
> + * @inode: File inode
> + * @offset: The offset where the hole will begin
> + * @len: The length of the hole
> + *
> + * Returns: 0 on sucess or negative on failure
> + */
> +
> +int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
> +{
> + struct inode *inode = file->f_path.dentry->d_inode;
> + if (!S_ISREG(inode->i_mode))
> + return -ENOTSUPP;
> +
> + if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> + /* TODO: Add support for non extent hole punching */
> + return -ENOTSUPP;
> + }
> +
> + return ext4_ext_punch_hole(file, offset, length);
> +}
> +
> +/*
> * ext4_truncate()
> *
> * We block out ext4_get_block() block instantiations across the entire
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