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Message-ID: <4DADCAF4.8000402@linux.vnet.ibm.com>
Date: Tue, 19 Apr 2011 10:48:36 -0700
From: Allison Henderson <achender@...ux.vnet.ibm.com>
To: Yongqiang Yang <xiaoqiangnk@...il.com>
CC: linux-ext4@...r.kernel.org
Subject: Re: [Ext4 punch hole 5/6 v5] Ext4 Punch Hole Support: Map blocks
punch hole flag
On 4/19/2011 1:35 AM, Yongqiang Yang wrote:
> On Tue, Apr 19, 2011 at 3:43 PM, Allison Henderson
> <achender@...ux.vnet.ibm.com> wrote:
>> This patch adds a new flag to map blocks that specifies
>> the given range of blocks should be punched out. Extents
>> are first converted to uninitialized extents before they are
>> punched out. Because punching a hole may require that the
>> extent be split, it is possible that the splitting may need
>> more blocks than are available. To deal with this, reserved
>> blocks are temporarily borrowed to allow the split to proceed.
>> The borrowed blocks are then returned after the hole punch has
>> released more blocks.
>>
>> The routine then returns the number of blocks successfully
>> punched out.
>>
>> Signed-off-by: Allison Henderson<achender@...ibm.com>
>> ---
>> :100644 100644 e3a721a... d97bc87... M fs/ext4/extents.c
>> fs/ext4/extents.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++------
>> 1 files changed, 88 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>> index e3a721a..d97bc87 100644
>> --- a/fs/ext4/extents.c
>> +++ b/fs/ext4/extents.c
>> @@ -3456,15 +3456,19 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
>> ext4_fsblk_t newblock = 0;
>> int err = 0, depth, ret;
>> unsigned int allocated = 0;
>> + unsigned int punched_out = 0;
>> + unsigned int result = 0;
>> struct ext4_allocation_request ar;
>> ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
>> + struct ext4_map_blocks punch_map;
>>
>> ext_debug("blocks %u/%u requested for inode %lu\n",
>> map->m_lblk, map->m_len, inode->i_ino);
>> trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
>>
>> /* check in cache */
>> - if (ext4_ext_in_cache(inode, map->m_lblk,&newex)) {
>> + if (ext4_ext_in_cache(inode, map->m_lblk,&newex)&&
>> + ((flags& EXT4_GET_BLOCKS_PUNCH_OUT_EXT) == 0)) {
>> if (!newex.ee_start_lo&& !newex.ee_start_hi) {
>> if ((flags& EXT4_GET_BLOCKS_CREATE) == 0) {
>> /*
>> @@ -3529,16 +3533,85 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
>> ext_debug("%u fit into %u:%d -> %llu\n", map->m_lblk,
>> ee_block, ee_len, newblock);
>>
>> - /* Do not put uninitialized extent in the cache */
>> - if (!ext4_ext_is_uninitialized(ex)) {
>> - ext4_ext_put_in_cache(inode, ee_block,
>> - ee_len, ee_start);
>> - goto out;
>> + if ((flags& EXT4_GET_BLOCKS_PUNCH_OUT_EXT) == 0) {
>> + /*
>> + * Do not put uninitialized extent
>> + * in the cache
>> + */
>> + if (!ext4_ext_is_uninitialized(ex)) {
>> + ext4_ext_put_in_cache(inode, ee_block,
>> + ee_len, ee_start);
>> + goto out;
>> + }
>> + ret = ext4_ext_handle_uninitialized_extents(
>> + handle, inode, map, path, flags,
>> + allocated, newblock);
>> + return ret;
>> }
>> - ret = ext4_ext_handle_uninitialized_extents(handle,
>> - inode, map, path, flags, allocated,
>> - newblock);
>> - return ret;
>> +
>> + /*
>> + * Punch out the map length, but only to the
>> + * end of the extent
>> + */
>> + punched_out = allocated< map->m_len ?
>> + allocated : map->m_len;
>> +
>> + /*
>> + * Sense extents need to be converted to
>> + * uninitialized, they must fit in an
>> + * uninitialized extent
>> + */
>> + if (punched_out> EXT_UNINIT_MAX_LEN)
>> + punched_out = EXT_UNINIT_MAX_LEN;
>> +
>> + punch_map.m_lblk = map->m_lblk;
>> + punch_map.m_pblk = newblock;
>> + punch_map.m_len = punched_out;
>> + punch_map.m_flags = 0;
>> +
>> + /* Check to see if the extent needs to be split */
>> + if (punch_map.m_len != ee_len ||
>> + punch_map.m_lblk != ee_block) {
>> +
>> + ret = ext4_ext_split_extents(handle, inode,
>> +&punch_map, path,
>> + EXT4_GET_BLOCKS_PRE_IO |
>> + EXT4_HAS_FREE_BLKS_USE_ROOTBLKS,
>> + 0);
>> +
>> + if (ret< 0) {
>> + err = ret;
>> + goto out2;
>> + }
>> + /*
>> + * find extent for the block at
>> + * the start of the hole
>> + */
>> + ext4_ext_drop_refs(path);
>> + kfree(path);
>> +
>> + path = ext4_ext_find_extent(inode,
>> + map->m_lblk, NULL);
>> + if (IS_ERR(path)) {
>> + err = PTR_ERR(path);
>> + path = NULL;
>> + goto out2;
>> + }
>> +
>> + depth = ext_depth(inode);
>> + ex = path[depth].p_ext;
>> + ee_len = ext4_ext_get_actual_len(ex);
>> + ee_block = le32_to_cpu(ex->ee_block);
>> + ee_start = ext4_ext_pblock(ex);
>> +
>> + }
>> +
>> + ext4_ext_mark_uninitialized(ex);
> Is this change journaled?
Hi there,
Yes, the ext4_ext_map_blocks routine requires a journal handle as a parameter, so the calling function is required to set up the journal.
>
>> +
>> + err = ext4_ext_remove_space(inode, map->m_lblk,
>> + map->m_lblk + punched_out);
>> +
>> + goto out2;
>> }
>> }
>>
>> @@ -3683,7 +3756,11 @@ out2:
>> }
>> trace_ext4_ext_map_blocks_exit(inode, map->m_lblk,
>> newblock, map->m_len, err ? err : allocated);
>> - return err ? err : allocated;
>> +
>> + result = (flags& EXT4_GET_BLOCKS_PUNCH_OUT_EXT) ?
>> + punched_out : allocated;
>> +
>> + return err ? err : result;
>> }
>>
>> void ext4_ext_truncate(struct inode *inode)
>> --
>> 1.7.1
>>
>> --
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>
>
>
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