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Message-ID: <4DCD5E87.5000607@linux.vnet.ibm.com>
Date:	Fri, 13 May 2011 09:38:31 -0700
From:	Allison Henderson <achender@...ux.vnet.ibm.com>
To:	Yongqiang Yang <xiaoqiangnk@...il.com>
CC:	Mingming Cao <cmm@...ibm.com>, linux-ext4@...r.kernel.org,
	tytso@....edu
Subject: Re: [PATCH v2 3/3] ext4:Reimplement convert and split_unwritten.

On 5/12/2011 7:06 PM, Yongqiang Yang wrote:
> On Fri, May 13, 2011 at 5:26 AM, Mingming Cao<cmm@...ibm.com>  wrote:
>> On Mon, 2011-05-02 at 19:05 -0700, Yongqiang Yang wrote:
>>> v0->v1:
>>>    -- ext4_ext_convert_initialized() zeroout whole extent when the extent's
>>>       length is less than 14.
>>>
>>> convert and split unwritten are reimplemented based on ext4_split_extent()
>>> added in last patch.
>>>
>>> Signed-off-by: Yongqiang Yang<xiaoqiangnk@...il.com>
>>> Tested-by: Allison Henderson<achender@...ux.vnet.ibm.com>
>>> ---
>>>   fs/ext4/extents.c |  480 ++++++++---------------------------------------------
>>>   1 files changed, 72 insertions(+), 408 deletions(-)
>>>
>>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>>> index db1d67c..9e7c7b3 100644
>>> --- a/fs/ext4/extents.c
>>> +++ b/fs/ext4/extents.c
>>> @@ -2757,17 +2757,13 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
>>>                                           struct ext4_map_blocks *map,
>>>                                           struct ext4_ext_path *path)
>>>   {
>>> -     struct ext4_extent *ex, newex, orig_ex;
>>> -     struct ext4_extent *ex1 = NULL;
>>> -     struct ext4_extent *ex2 = NULL;
>>> -     struct ext4_extent *ex3 = NULL;
>>> -     struct ext4_extent_header *eh;
>>> +     struct ext4_map_blocks split_map;
>>> +     struct ext4_extent zero_ex;
>>> +     struct ext4_extent *ex;
>>>        ext4_lblk_t ee_block, eof_block;
>>>        unsigned int allocated, ee_len, depth;
>>> -     ext4_fsblk_t newblock;
>>>        int err = 0;
>>> -     int ret = 0;
>>> -     int may_zeroout;
>>> +     int split_flag = 0;
>>>
>>>        ext_debug("ext4_ext_convert_to_initialized: inode %lu, logical"
>>>                "block %llu, max_blocks %u\n", inode->i_ino,
>>> @@ -2779,280 +2775,87 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
>>>                eof_block = map->m_lblk + map->m_len;
>>>
>>>        depth = ext_depth(inode);
>>> -     eh = path[depth].p_hdr;
>>>        ex = path[depth].p_ext;
>>>        ee_block = le32_to_cpu(ex->ee_block);
>>>        ee_len = ext4_ext_get_actual_len(ex);
>>>        allocated = ee_len - (map->m_lblk - ee_block);
>>> -     newblock = map->m_lblk - ee_block + ext4_ext_pblock(ex);
>>> -
>>> -     ex2 = ex;
>>> -     orig_ex.ee_block = ex->ee_block;
>>> -     orig_ex.ee_len   = cpu_to_le16(ee_len);
>>> -     ext4_ext_store_pblock(&orig_ex, ext4_ext_pblock(ex));
>>>
>>> +     WARN_ON(map->m_lblk<  ee_block);
>>>        /*
>>>         * It is safe to convert extent to initialized via explicit
>>>         * zeroout only if extent is fully insde i_size or new_size.
>>>         */
>>> -     may_zeroout = ee_block + ee_len<= eof_block;
>>> +     split_flag |= ee_block + ee_len<= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
>>>
>>> -     err = ext4_ext_get_access(handle, inode, path + depth);
>>> -     if (err)
>>> -             goto out;
>>>        /* If extent has less than 2*EXT4_EXT_ZERO_LEN zerout directly */
>>> -     if (ee_len<= 2*EXT4_EXT_ZERO_LEN&&  may_zeroout) {
>>> -             err =  ext4_ext_zeroout(inode,&orig_ex);
>>> +     if (ee_len<= 2*EXT4_EXT_ZERO_LEN&&
>>> +         (EXT4_EXT_MAY_ZEROOUT&  split_flag)) {
>>> +             err = ext4_ext_zeroout(inode, ex);
>>>                if (err)
>>> -                     goto fix_extent_len;
>>> -             /* update the extent length and mark as initialized */
>>> -             ex->ee_block = orig_ex.ee_block;
>>> -             ex->ee_len   = orig_ex.ee_len;
>>> -             ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -             ext4_ext_dirty(handle, inode, path + depth);
>>> -             /* zeroed the full extent */
>>> -             return allocated;
>>> -     }
>>> -
>>> -     /* ex1: ee_block to map->m_lblk - 1 : uninitialized */
>>> -     if (map->m_lblk>  ee_block) {
>>> -             ex1 = ex;
>>> -             ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
>>> -             ext4_ext_mark_uninitialized(ex1);
>>> -             ex2 =&newex;
>>> -     }
>>> -     /*
>>> -      * for sanity, update the length of the ex2 extent before
>>> -      * we insert ex3, if ex1 is NULL. This is to avoid temporary
>>> -      * overlap of blocks.
>>> -      */
>>> -     if (!ex1&&  allocated>  map->m_len)
>>> -             ex2->ee_len = cpu_to_le16(map->m_len);
>>> -     /* ex3: to ee_block + ee_len : uninitialised */
>>> -     if (allocated>  map->m_len) {
>>> -             unsigned int newdepth;
>>> -             /* If extent has less than EXT4_EXT_ZERO_LEN zerout directly */
>>> -             if (allocated<= EXT4_EXT_ZERO_LEN&&  may_zeroout) {
>>> -                     /*
>>> -                      * map->m_lblk == ee_block is handled by the zerouout
>>> -                      * at the beginning.
>>> -                      * Mark first half uninitialized.
>>> -                      * Mark second half initialized and zero out the
>>> -                      * initialized extent
>>> -                      */
>>> -                     ex->ee_block = orig_ex.ee_block;
>>> -                     ex->ee_len   = cpu_to_le16(ee_len - allocated);
>>> -                     ext4_ext_mark_uninitialized(ex);
>>> -                     ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -                     ext4_ext_dirty(handle, inode, path + depth);
>>> -
>>> -                     ex3 =&newex;
>>> -                     ex3->ee_block = cpu_to_le32(map->m_lblk);
>>> -                     ext4_ext_store_pblock(ex3, newblock);
>>> -                     ex3->ee_len = cpu_to_le16(allocated);
>>> -                     err = ext4_ext_insert_extent(handle, inode, path,
>>> -                                                     ex3, 0);
>>> -                     if (err == -ENOSPC) {
>>> -                             err =  ext4_ext_zeroout(inode,&orig_ex);
>>> -                             if (err)
>>> -                                     goto fix_extent_len;
>>> -                             ex->ee_block = orig_ex.ee_block;
>>> -                             ex->ee_len   = orig_ex.ee_len;
>>> -                             ext4_ext_store_pblock(ex,
>>> -                                     ext4_ext_pblock(&orig_ex));
>>> -                             ext4_ext_dirty(handle, inode, path + depth);
>>> -                             /* blocks available from map->m_lblk */
>>> -                             return allocated;
>>> -
>>> -                     } else if (err)
>>> -                             goto fix_extent_len;
>>> -
>>> -                     /*
>>> -                      * We need to zero out the second half because
>>> -                      * an fallocate request can update file size and
>>> -                      * converting the second half to initialized extent
>>> -                      * implies that we can leak some junk data to user
>>> -                      * space.
>>> -                      */
>>> -                     err =  ext4_ext_zeroout(inode, ex3);
>>> -                     if (err) {
>>> -                             /*
>>> -                              * We should actually mark the
>>> -                              * second half as uninit and return error
>>> -                              * Insert would have changed the extent
>>> -                              */
>>> -                             depth = ext_depth(inode);
>>> -                             ext4_ext_drop_refs(path);
>>> -                             path = ext4_ext_find_extent(inode, map->m_lblk,
>>> -                                                         path);
>>> -                             if (IS_ERR(path)) {
>>> -                                     err = PTR_ERR(path);
>>> -                                     return err;
>>> -                             }
>>> -                             /* get the second half extent details */
>>> -                             ex = path[depth].p_ext;
>>> -                             err = ext4_ext_get_access(handle, inode,
>>> -                                                             path + depth);
>>> -                             if (err)
>>> -                                     return err;
>>> -                             ext4_ext_mark_uninitialized(ex);
>>> -                             ext4_ext_dirty(handle, inode, path + depth);
>>> -                             return err;
>>> -                     }
>>> -
>>> -                     /* zeroed the second half */
>>> -                     return allocated;
>>> -             }
>>> -             ex3 =&newex;
>>> -             ex3->ee_block = cpu_to_le32(map->m_lblk + map->m_len);
>>> -             ext4_ext_store_pblock(ex3, newblock + map->m_len);
>>> -             ex3->ee_len = cpu_to_le16(allocated - map->m_len);
>>> -             ext4_ext_mark_uninitialized(ex3);
>>> -             err = ext4_ext_insert_extent(handle, inode, path, ex3, 0);
>>> -             if (err == -ENOSPC&&  may_zeroout) {
>>> -                     err =  ext4_ext_zeroout(inode,&orig_ex);
>>> -                     if (err)
>>> -                             goto fix_extent_len;
>>> -                     /* update the extent length and mark as initialized */
>>> -                     ex->ee_block = orig_ex.ee_block;
>>> -                     ex->ee_len   = orig_ex.ee_len;
>>> -                     ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -                     ext4_ext_dirty(handle, inode, path + depth);
>>> -                     /* zeroed the full extent */
>>> -                     /* blocks available from map->m_lblk */
>>> -                     return allocated;
>>> -
>>> -             } else if (err)
>>> -                     goto fix_extent_len;
>>> -             /*
>>> -              * The depth, and hence eh&  ex might change
>>> -              * as part of the insert above.
>>> -              */
>>> -             newdepth = ext_depth(inode);
>>> -             /*
>>> -              * update the extent length after successful insert of the
>>> -              * split extent
>>> -              */
>>> -             ee_len -= ext4_ext_get_actual_len(ex3);
>>> -             orig_ex.ee_len = cpu_to_le16(ee_len);
>>> -             may_zeroout = ee_block + ee_len<= eof_block;
>>> -
>>> -             depth = newdepth;
>>> -             ext4_ext_drop_refs(path);
>>> -             path = ext4_ext_find_extent(inode, map->m_lblk, path);
>>> -             if (IS_ERR(path)) {
>>> -                     err = PTR_ERR(path);
>>>                        goto out;
>>> -             }
>>> -             eh = path[depth].p_hdr;
>>> -             ex = path[depth].p_ext;
>>> -             if (ex2 !=&newex)
>>> -                     ex2 = ex;
>>>
>>>                err = ext4_ext_get_access(handle, inode, path + depth);
>>>                if (err)
>>>                        goto out;
>>> -
>>> -             allocated = map->m_len;
>>> -
>>> -             /* If extent has less than EXT4_EXT_ZERO_LEN and we are trying
>>> -              * to insert a extent in the middle zerout directly
>>> -              * otherwise give the extent a chance to merge to left
>>> -              */
>>> -             if (le16_to_cpu(orig_ex.ee_len)<= EXT4_EXT_ZERO_LEN&&
>>> -                     map->m_lblk != ee_block&&  may_zeroout) {
>>> -                     err =  ext4_ext_zeroout(inode,&orig_ex);
>>> -                     if (err)
>>> -                             goto fix_extent_len;
>>> -                     /* update the extent length and mark as initialized */
>>> -                     ex->ee_block = orig_ex.ee_block;
>>> -                     ex->ee_len   = orig_ex.ee_len;
>>> -                     ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -                     ext4_ext_dirty(handle, inode, path + depth);
>>> -                     /* zero out the first half */
>>> -                     /* blocks available from map->m_lblk */
>>> -                     return allocated;
>>> -             }
>>> -     }
>>> -     /*
>>> -      * If there was a change of depth as part of the
>>> -      * insertion of ex3 above, we need to update the length
>>> -      * of the ex1 extent again here
>>> -      */
>>> -     if (ex1&&  ex1 != ex) {
>>> -             ex1 = ex;
>>> -             ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
>>> -             ext4_ext_mark_uninitialized(ex1);
>>> -             ex2 =&newex;
>>> -     }
>>> -     /* ex2: map->m_lblk to map->m_lblk + maxblocks-1 : initialised */
>>> -     ex2->ee_block = cpu_to_le32(map->m_lblk);
>>> -     ext4_ext_store_pblock(ex2, newblock);
>>> -     ex2->ee_len = cpu_to_le16(allocated);
>>> -     if (ex2 != ex)
>>> -             goto insert;
>>> -     /*
>>> -      * New (initialized) extent starts from the first block
>>> -      * in the current extent. i.e., ex2 == ex
>>> -      * We have to see if it can be merged with the extent
>>> -      * on the left.
>>> -      */
>>> -     if (ex2>  EXT_FIRST_EXTENT(eh)) {
>>> -             /*
>>> -              * To merge left, pass "ex2 - 1" to try_to_merge(),
>>> -              * since it merges towards right _only_.
>>> -              */
>>> -             ret = ext4_ext_try_to_merge(inode, path, ex2 - 1);
>>> -             if (ret) {
>>> -                     err = ext4_ext_correct_indexes(handle, inode, path);
>>> -                     if (err)
>>> -                             goto out;
>>> -                     depth = ext_depth(inode);
>>> -                     ex2--;
>>> -             }
>>> +             ext4_ext_mark_initialized(ex);
>>> +             ext4_ext_try_to_merge(inode, path, ex);
>>> +             err = ext4_ext_dirty(handle, inode, path + depth);
>>> +             goto out;
>>>        }
>>> +
>>>        /*
>>> -      * Try to Merge towards right. This might be required
>>> -      * only when the whole extent is being written to.
>>> -      * i.e. ex2 == ex and ex3 == NULL.
>>> +      * four cases:
>>> +      * 1. split the extent into three extents.
>>> +      * 2. split the extent into two extents, zeroout the first half.
>>> +      * 3. split the extent into two extents, zeroout the second half.
>>> +      * 4. split the extent into two extents with out zeroout.
>>>         */
>>> -     if (!ex3) {
>>> -             ret = ext4_ext_try_to_merge(inode, path, ex2);
>>> -             if (ret) {
>>> -                     err = ext4_ext_correct_indexes(handle, inode, path);
>>> +     split_map.m_lblk = map->m_lblk;
>>> +     split_map.m_len = map->m_len;
>>> +
>>> +     if (allocated>  map->m_len) {
>>> +             if (allocated<= EXT4_EXT_ZERO_LEN&&
>>> +                 (EXT4_EXT_MAY_ZEROOUT&  split_flag)) {
>>> +                     /* case 3 */
>>> +                     zero_ex.ee_block =
>>> +                                      cpu_to_le32(map->m_lblk + map->m_len);
>>> +                     zero_ex.ee_len = cpu_to_le16(allocated - map->m_len);
>> Hmm, the original code zero out the entire [map->m_lblk, allocated],
>> where here we only zero out a portion of it. it doesnt match the split
>> len below also.
> Yeah, I just zero out a portion of it which is not the requested.  I
> think the requested part will have non-zero data.
>>
>>
>>> +                     ext4_ext_store_pblock(&zero_ex,
>>> +                             ext4_ext_pblock(ex) + map->m_lblk - ee_block);
>>> +                     err = ext4_ext_zeroout(inode,&zero_ex);
>>>                        if (err)
>>>                                goto out;
>>> +                     split_map.m_lblk = map->m_lblk;
>>> +                     split_map.m_len = allocated;
>>> +             } else if ((map->m_lblk - ee_block + map->m_len<
>>> +                        EXT4_EXT_ZERO_LEN)&&
>>> +                        (EXT4_EXT_MAY_ZEROOUT&  split_flag)) {
>>> +                     /* case 2 */
>>> +                     if (map->m_lblk != ee_block) {
>>> +                             zero_ex.ee_block = ex->ee_block;
>>> +                             zero_ex.ee_len = cpu_to_le16(map->m_lblk -
>>> +                                                     ee_block);
>> similar to above, the original code zero out the entire [ex->ee_block,
>> map->m_lblk - ee_block + map->m_len], where here we only zero out a
>> portion of it. same to the mismatch of the split len also.
> Similar to above.  Just a optimization.
>>
>>
>>> +                             ext4_ext_store_pblock(&zero_ex,
>>> +                                                   ext4_ext_pblock(ex));
>>> +                             err = ext4_ext_zeroout(inode,&zero_ex);
>>> +                             if (err)
>>> +                                     goto out;
>>> +                     }
>>> +
>>>   -                    allocated = map->m_lblk - ee_block + map->m_len;
>>> +
>>> +                     split_map.m_lblk = ee_block;
>>> +                     split_map.m_len =  map->m_lblk - ee_block + map->m_len;
> +                          allocated = map->m_len;
>>
>> I am also puzzled whether the zeroed-out extent get marked as
>> initialized, as done in original patch. The whole point of zero out is
>> to avoid frequent split of the unitizlized extent if the extent is
>> short. I will take a closer look at the previous patch.
>>
>> Another issue, upon success, "allocated" will return from this function.
>> But here allocated is the zero out length that start from ee_block, not
>> the length from map->m_lblk. this is wrong, the caller
>> ext4_ext_map_blocks expecting the length of mapped blocks from
>> map->m_lblk.  We now return more mapped blocks than what really done.  I
>> suspect the fsx error come from this bug.
> Yeah. it is a bug.
>
> Hi Allison,
>
> Could you test with modification above?  Here is a bug. I will also test it.
>
> Thank you.

Hi all,

Well, I tried the above fix this morning, but it looks like it was only 
able to run about a half hour.  Some good news though, last night I 
tried just changing "zero_ex.ee_len = cpu_to_le16(allocated - 
map->m_len);" to "zero_ex.ee_len = cpu_to_le16(allocated);" in case 3 
and it ran all night with no problems.  Maybe we need both changes then. 
  I'll start another test run today.

Allison Henderson

>>
>>>                }
>>
>>
>>>        }
>>> -     /* Mark modified extent as dirty */
>>> -     err = ext4_ext_dirty(handle, inode, path + depth);
>>> -     goto out;
>>> -insert:
>>> -     err = ext4_ext_insert_extent(handle, inode, path,&newex, 0);
>>> -     if (err == -ENOSPC&&  may_zeroout) {
>>> -             err =  ext4_ext_zeroout(inode,&orig_ex);
>>> -             if (err)
>>> -                     goto fix_extent_len;
>>> -             /* update the extent length and mark as initialized */
>>> -             ex->ee_block = orig_ex.ee_block;
>>> -             ex->ee_len   = orig_ex.ee_len;
>>> -             ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -             ext4_ext_dirty(handle, inode, path + depth);
>>> -             /* zero out the first half */
>>> -             return allocated;
>>> -     } else if (err)
>>> -             goto fix_extent_len;
>>> +
>>> +     allocated = ext4_split_extent(handle, inode, path,
>>> +&split_map, split_flag, 0);
>>> +     if (allocated<  0)
>>> +             err = allocated;
>>> +
>>>   out:
>>> -     ext4_ext_show_leaf(inode, path);
>>>        return err ? err : allocated;
>>> -
>>> -fix_extent_len:
>>> -     ex->ee_block = orig_ex.ee_block;
>>> -     ex->ee_len   = orig_ex.ee_len;
>>> -     ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -     ext4_ext_mark_uninitialized(ex);
>>> -     ext4_ext_dirty(handle, inode, path + depth);
>>> -     return err;
>>>   }
>>>
>>>   /*
>>> @@ -3083,15 +2886,11 @@ static int ext4_split_unwritten_extents(handle_t *handle,
>>>                                        struct ext4_ext_path *path,
>>>                                        int flags)
>>>   {
>>> -     struct ext4_extent *ex, newex, orig_ex;
>>> -     struct ext4_extent *ex1 = NULL;
>>> -     struct ext4_extent *ex2 = NULL;
>>> -     struct ext4_extent *ex3 = NULL;
>>> -     ext4_lblk_t ee_block, eof_block;
>>> -     unsigned int allocated, ee_len, depth;
>>> -     ext4_fsblk_t newblock;
>>> -     int err = 0;
>>> -     int may_zeroout;
>>> +     ext4_lblk_t eof_block;
>>> +     ext4_lblk_t ee_block;
>>> +     struct ext4_extent *ex;
>>> +     unsigned int ee_len;
>>> +     int split_flag = 0, depth;
>>>
>>>        ext_debug("ext4_split_unwritten_extents: inode %lu, logical"
>>>                "block %llu, max_blocks %u\n", inode->i_ino,
>>> @@ -3101,155 +2900,20 @@ static int ext4_split_unwritten_extents(handle_t *handle,
>>>                inode->i_sb->s_blocksize_bits;
>>>        if (eof_block<  map->m_lblk + map->m_len)
>>>                eof_block = map->m_lblk + map->m_len;
>>> -
>>> -     depth = ext_depth(inode);
>>> -     ex = path[depth].p_ext;
>>> -     ee_block = le32_to_cpu(ex->ee_block);
>>> -     ee_len = ext4_ext_get_actual_len(ex);
>>> -     allocated = ee_len - (map->m_lblk - ee_block);
>>> -     newblock = map->m_lblk - ee_block + ext4_ext_pblock(ex);
>>> -
>>> -     ex2 = ex;
>>> -     orig_ex.ee_block = ex->ee_block;
>>> -     orig_ex.ee_len   = cpu_to_le16(ee_len);
>>> -     ext4_ext_store_pblock(&orig_ex, ext4_ext_pblock(ex));
>>> -
>>>        /*
>>>         * It is safe to convert extent to initialized via explicit
>>>         * zeroout only if extent is fully insde i_size or new_size.
>>>         */
>>> -     may_zeroout = ee_block + ee_len<= eof_block;
>>> -
>>> -     /*
>>> -      * If the uninitialized extent begins at the same logical
>>> -      * block where the write begins, and the write completely
>>> -      * covers the extent, then we don't need to split it.
>>> -      */
>>> -     if ((map->m_lblk == ee_block)&&  (allocated<= map->m_len))
>>> -             return allocated;
>>> -
>>> -     err = ext4_ext_get_access(handle, inode, path + depth);
>>> -     if (err)
>>> -             goto out;
>>> -     /* ex1: ee_block to map->m_lblk - 1 : uninitialized */
>>> -     if (map->m_lblk>  ee_block) {
>>> -             ex1 = ex;
>>> -             ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
>>> -             ext4_ext_mark_uninitialized(ex1);
>>> -             ex2 =&newex;
>>> -     }
>>> -     /*
>>> -      * for sanity, update the length of the ex2 extent before
>>> -      * we insert ex3, if ex1 is NULL. This is to avoid temporary
>>> -      * overlap of blocks.
>>> -      */
>>> -     if (!ex1&&  allocated>  map->m_len)
>>> -             ex2->ee_len = cpu_to_le16(map->m_len);
>>> -     /* ex3: to ee_block + ee_len : uninitialised */
>>> -     if (allocated>  map->m_len) {
>>> -             unsigned int newdepth;
>>> -             ex3 =&newex;
>>> -             ex3->ee_block = cpu_to_le32(map->m_lblk + map->m_len);
>>> -             ext4_ext_store_pblock(ex3, newblock + map->m_len);
>>> -             ex3->ee_len = cpu_to_le16(allocated - map->m_len);
>>> -             ext4_ext_mark_uninitialized(ex3);
>>> -             err = ext4_ext_insert_extent(handle, inode, path, ex3, flags);
>>> -             if (err == -ENOSPC&&  may_zeroout) {
>>> -                     err =  ext4_ext_zeroout(inode,&orig_ex);
>>> -                     if (err)
>>> -                             goto fix_extent_len;
>>> -                     /* update the extent length and mark as initialized */
>>> -                     ex->ee_block = orig_ex.ee_block;
>>> -                     ex->ee_len   = orig_ex.ee_len;
>>> -                     ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -                     ext4_ext_dirty(handle, inode, path + depth);
>>> -                     /* zeroed the full extent */
>>> -                     /* blocks available from map->m_lblk */
>>> -                     return allocated;
>>> -
>>> -             } else if (err)
>>> -                     goto fix_extent_len;
>>> -             /*
>>> -              * The depth, and hence eh&  ex might change
>>> -              * as part of the insert above.
>>> -              */
>>> -             newdepth = ext_depth(inode);
>>> -             /*
>>> -              * update the extent length after successful insert of the
>>> -              * split extent
>>> -              */
>>> -             ee_len -= ext4_ext_get_actual_len(ex3);
>>> -             orig_ex.ee_len = cpu_to_le16(ee_len);
>>> -             may_zeroout = ee_block + ee_len<= eof_block;
>>> -
>>> -             depth = newdepth;
>>> -             ext4_ext_drop_refs(path);
>>> -             path = ext4_ext_find_extent(inode, map->m_lblk, path);
>>> -             if (IS_ERR(path)) {
>>> -                     err = PTR_ERR(path);
>>> -                     goto out;
>>> -             }
>>> -             ex = path[depth].p_ext;
>>> -             if (ex2 !=&newex)
>>> -                     ex2 = ex;
>>> +     depth = ext_depth(inode);
>>> +     ex = path[depth].p_ext;
>>> +     ee_block = le32_to_cpu(ex->ee_block);
>>> +     ee_len = ext4_ext_get_actual_len(ex);
>>>
>>> -             err = ext4_ext_get_access(handle, inode, path + depth);
>>> -             if (err)
>>> -                     goto out;
>>> +     split_flag |= ee_block + ee_len<= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
>>> +     split_flag |= EXT4_EXT_MARK_UNINIT2;
>>>
>>> -             allocated = map->m_len;
>>> -     }
>>> -     /*
>>> -      * If there was a change of depth as part of the
>>> -      * insertion of ex3 above, we need to update the length
>>> -      * of the ex1 extent again here
>>> -      */
>>> -     if (ex1&&  ex1 != ex) {
>>> -             ex1 = ex;
>>> -             ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
>>> -             ext4_ext_mark_uninitialized(ex1);
>>> -             ex2 =&newex;
>>> -     }
>>> -     /*
>>> -      * ex2: map->m_lblk to map->m_lblk + map->m_len-1 : to be written
>>> -      * using direct I/O, uninitialised still.
>>> -      */
>>> -     ex2->ee_block = cpu_to_le32(map->m_lblk);
>>> -     ext4_ext_store_pblock(ex2, newblock);
>>> -     ex2->ee_len = cpu_to_le16(allocated);
>>> -     ext4_ext_mark_uninitialized(ex2);
>>> -     if (ex2 != ex)
>>> -             goto insert;
>>> -     /* Mark modified extent as dirty */
>>> -     err = ext4_ext_dirty(handle, inode, path + depth);
>>> -     ext_debug("out here\n");
>>> -     goto out;
>>> -insert:
>>> -     err = ext4_ext_insert_extent(handle, inode, path,&newex, flags);
>>> -     if (err == -ENOSPC&&  may_zeroout) {
>>> -             err =  ext4_ext_zeroout(inode,&orig_ex);
>>> -             if (err)
>>> -                     goto fix_extent_len;
>>> -             /* update the extent length and mark as initialized */
>>> -             ex->ee_block = orig_ex.ee_block;
>>> -             ex->ee_len   = orig_ex.ee_len;
>>> -             ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -             ext4_ext_dirty(handle, inode, path + depth);
>>> -             /* zero out the first half */
>>> -             return allocated;
>>> -     } else if (err)
>>> -             goto fix_extent_len;
>>> -out:
>>> -     ext4_ext_show_leaf(inode, path);
>>> -     return err ? err : allocated;
>>> -
>>> -fix_extent_len:
>>> -     ex->ee_block = orig_ex.ee_block;
>>> -     ex->ee_len   = orig_ex.ee_len;
>>> -     ext4_ext_store_pblock(ex, ext4_ext_pblock(&orig_ex));
>>> -     ext4_ext_mark_uninitialized(ex);
>>> -     ext4_ext_dirty(handle, inode, path + depth);
>>> -     return err;
>>> +     flags |= EXT4_GET_BLOCKS_PRE_IO;
>>> +     return ext4_split_extent(handle, inode, path, map, split_flag, flags);
>>>   }
>>>
>>>   static int ext4_convert_unwritten_extents_endio(handle_t *handle,
>>
>>
>>
>
>
>

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