diff mbox

ext4: always pre-allocate max depth for path

Message ID C214BF91-E916-4790-93AD-0849767A9F8E@intel.com
State Superseded, archived
Headers show

Commit Message

Faccini, Bruno June 16, 2016, 4:53 p.m. UTC
From: Bruno Faccini <bruno.faccini@intel.com>

I have first found this way to fix holes in previous ext4 layers versions
where an array of struct ext4_ext_path had been allocated with an arbitrary
evaluated size and finally could overrun upon ext_depth() growth outside
i_data_sem protection. But it seems it can still help with recent ext4
version, to avoid re-allocation need and overhead when it can be allocated
to max possible extent depth (ie, 5 presently) at first time and for a low
cost regarding its memory foot-print, it should also avoid further invalid
dereference by underlying callers sharing same ppath (with present
inter-routines path re-use scheme), and also upon re-allocation error.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
---
 fs/ext4/ext4.h        |    3 +
 fs/ext4/extents.c     |  113 ++++++++++++++++++++++++++--------------
 fs/ext4/move_extent.c |   10 +--
 fs/ext4/super.c       |    3 -
 4 files changed, 85 insertions(+), 44 deletions(-)

--

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Comments

kernel test robot June 16, 2016, 6:28 p.m. UTC | #1
Hi,

[auto build test ERROR on ext4/dev]
[also build test ERROR on v4.7-rc3 next-20160616]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Faccini-Bruno/ext4-always-pre-allocate-max-depth-for-path/20160617-005701
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: sh-sh7785lcr_32bit_defconfig (attached as .config)
compiler: sh4-linux-gnu-gcc (Debian 5.3.1-8) 5.3.1 20160205
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=sh 

All errors (new ones prefixed by >>):

   fs/built-in.o: In function `ext4_ext_init':
>> fs/ext4/extents.c:3108: undefined reference to `__divdi3'
>> fs/ext4/extents.c:3108: undefined reference to `__udivdi3'

vim +3108 fs/ext4/extents.c

  3102				      sizeof(struct ext4_extent_header)) /
  3103				     max(sizeof(struct ext4_extent),
  3104					 sizeof(struct ext4_extent_idx));
  3105	
  3106			/* compute maximum extents tree depth for a fully populated
  3107			 * file of max size made of only minimal/1-block extents */
> 3108			while (maxblocks > 0) {
  3109				maxblocks /= (sb->s_blocksize -
  3110					      sizeof(struct ext4_extent_header)) /
  3111					     max(sizeof(struct ext4_extent),

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
kernel test robot June 16, 2016, 6:54 p.m. UTC | #2
Hi,

[auto build test ERROR on ext4/dev]
[also build test ERROR on v4.7-rc3 next-20160616]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Faccini-Bruno/ext4-always-pre-allocate-max-depth-for-path/20160617-005701
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: arm-imote2_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 5.3.1-8) 5.3.1 20160205
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm 

All errors (new ones prefixed by >>):

>> ERROR: "__aeabi_ldivmod" [fs/ext4/ext4.ko] undefined!
>> ERROR: "__aeabi_uldivmod" [fs/ext4/ext4.ko] undefined!

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
kernel test robot June 16, 2016, 6:55 p.m. UTC | #3
Hi,

[auto build test ERROR on ext4/dev]
[also build test ERROR on v4.7-rc3 next-20160616]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Faccini-Bruno/ext4-always-pre-allocate-max-depth-for-path/20160617-005701
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
config: arm-orion5x_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 5.3.1-8) 5.3.1 20160205
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=arm 

All errors (new ones prefixed by >>):

   fs/built-in.o: In function `ext4_ext_init':
>> fs/ext4/extents.c:3096: undefined reference to `__aeabi_ldivmod'
>> fs/ext4/extents.c:3109: undefined reference to `__aeabi_uldivmod'

vim +3096 fs/ext4/extents.c

  3090	#endif
  3091			       , sb->s_id);
  3092	
  3093	
  3094			EXT4_SB(sb)->s_max_ext_tree_depth = 1;
  3095	
> 3096			maxblocks = sb->s_maxbytes / sb->s_blocksize;
  3097	
  3098			/* 1st/root level/node of extents tree stands in i_data and
  3099			 * entries stored in tree nodes can be of type ext4_extent
  3100			 * (leaf node) or ext4_extent_idx (internal node) */
  3101			maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -
  3102				      sizeof(struct ext4_extent_header)) /
  3103				     max(sizeof(struct ext4_extent),
  3104					 sizeof(struct ext4_extent_idx));
  3105	
  3106			/* compute maximum extents tree depth for a fully populated
  3107			 * file of max size made of only minimal/1-block extents */
  3108			while (maxblocks > 0) {
> 3109				maxblocks /= (sb->s_blocksize -
  3110					      sizeof(struct ext4_extent_header)) /
  3111					     max(sizeof(struct ext4_extent),
  3112						 sizeof(struct ext4_extent_idx));

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
Andreas Dilger June 16, 2016, 7:36 p.m. UTC | #4
On Jun 16, 2016, at 10:53 AM, Faccini, Bruno <bruno.faccini@intel.com> wrote:
> 
> From: Bruno Faccini <bruno.faccini@intel.com>
> 
> I have first found this way to fix holes in previous ext4 layers versions
> where an array of struct ext4_ext_path had been allocated with an arbitrary
> evaluated size and finally could overrun upon ext_depth() growth outside
> i_data_sem protection. But it seems it can still help with recent ext4
> version, to avoid re-allocation need and overhead when it can be allocated
> to max possible extent depth (ie, 5 presently) at first time and for a low
> cost regarding its memory foot-print, it should also avoid further invalid
> dereference by underlying callers sharing same ppath (with present
> inter-routines path re-use scheme), and also upon re-allocation error.
> 
> Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
> ---
> fs/ext4/ext4.h        |    3 +
> fs/ext4/extents.c     |  113 ++++++++++++++++++++++++++--------------
> fs/ext4/move_extent.c |   10 +--
> fs/ext4/super.c       |    3 -
> 4 files changed, 85 insertions(+), 44 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 1e20fa9..73d5866 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1340,6 +1340,9 @@ struct ext4_sb_info {
> 	unsigned long s_ext_extents;
> #endif
> 
> +	/* maximum possible extents tree depth, to be computed at mount time */
> +	unsigned int s_max_ext_tree_depth;
> +
> 	/* for buddy allocator */
> 	struct ext4_group_info ***s_group_info;
> 	struct inode *s_buddy_cache;
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index b52fea3..aee676d 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -871,19 +871,18 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
> 
> 	if (path) {
> 		ext4_ext_drop_refs(path);
> -		if (depth > path[0].p_maxdepth) {
> -			kfree(path);
> -			*orig_path = path = NULL;
> -		}
> -	}
> -	if (!path) {
> +		/* path has been allocated for the max possible depth
> +		 * so we can simply reuse it */
> +		/* XXX need to clear/zero old path content? */
> +	} else {
> 		/* account possible depth increase */
> -		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
> +		path = kzalloc(sizeof(struct ext4_ext_path) *
> +				EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,
> 				GFP_NOFS);
> 		if (unlikely(!path))
> 			return ERR_PTR(-ENOMEM);
> -		path[0].p_maxdepth = depth + 1;
> 	}
> +	path[0].p_maxdepth = depth + 1;
> 	path[0].p_hdr = eh;
> 	path[0].p_bh = NULL;
> 
> @@ -934,9 +933,11 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
> 
> err:
> 	ext4_ext_drop_refs(path);
> -	kfree(path);
> -	if (orig_path)
> -		*orig_path = NULL;
> +
> +	/* do not free *orig_path, it is likely to be referenced by callers */
> +	if (!orig_path)
> +		kfree(path);
> +
> 	return ERR_PTR(ret);
> }
> 
> @@ -2147,7 +2148,8 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
> 				    ext4_lblk_t block, ext4_lblk_t num,
> 				    struct fiemap_extent_info *fieinfo)
> {
> -	struct ext4_ext_path *path = NULL;
> +	struct ext4_ext_path *path = NULL, *orig_path = NULL;
> +	struct ext4_ext_path **orig_ppath = &orig_path;
> 	struct ext4_extent *ex;
> 	struct extent_status es;
> 	ext4_lblk_t next, next_del, start = 0, end = 0;
> @@ -2161,13 +2163,16 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
> 		/* find extent for this block */
> 		down_read(&EXT4_I(inode)->i_data_sem);
> 
> -		path = ext4_find_extent(inode, block, &path, 0);
> +		path = ext4_find_extent(inode, block, orig_ppath, 0);
> 		if (IS_ERR(path)) {
> 			up_read(&EXT4_I(inode)->i_data_sem);
> 			err = PTR_ERR(path);
> 			path = NULL;
> 			break;
> 		}
> +		if (!orig_path)
> +			orig_path = path;
> +		/* XXX else BUG_ON(path != orig_path); */
> 
> 		depth = ext_depth(inode);
> 		if (unlikely(path[depth].p_hdr == NULL)) {
> @@ -2287,8 +2292,8 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
> 		block = es.es_lblk + es.es_len;
> 	}
> 
> -	ext4_ext_drop_refs(path);
> -	kfree(path);
> +	ext4_ext_drop_refs(orig_path);
> +	kfree(orig_path);
> 	return err;
> }
> 
> @@ -2910,7 +2915,8 @@ again:
> 			path[k].p_block =
> 				le16_to_cpu(path[k].p_hdr->eh_entries)+1;
> 	} else {
> -		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1),
> +		path = kzalloc(sizeof(struct ext4_ext_path) *
> +			       EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,
> 			       GFP_NOFS);
> 		if (path == NULL) {
> 			ext4_journal_stop(handle);
> @@ -3051,13 +3057,14 @@ out:
>  */
> void ext4_ext_init(struct super_block *sb)
> {
> +	ext4_fsblk_t maxblocks;
> +
> 	/*
> 	 * possible initialization would be here
> 	 */
> 
> 	if (ext4_has_feature_extents(sb)) {
> -#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)

This debugging info shouldn't be printed for every mount.  This should be
kept under the original #ifdef:

#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || \
    defined(EXTENTS_STATS) || defined(EXT_DEBUG)


> -		printk(KERN_INFO "EXT4-fs: file extents enabled"
> +		printk(KERN_INFO "EXT4-fs (%s): file extents enabled"
> #ifdef AGGRESSIVE_TEST
> 		       ", aggressive tests"
> #endif
> @@ -3067,8 +3074,36 @@ void ext4_ext_init(struct super_block *sb)
> #ifdef EXTENTS_STATS
> 		       ", stats"
> #endif
> -		       "\n");
> +		       , sb->s_id);
> +
> +
> +		EXT4_SB(sb)->s_max_ext_tree_depth = 1;
> +
> +		maxblocks = sb->s_maxbytes / sb->s_blocksize;

To avoid the 64-bit divide on 32-bit platforms this can be:

		maxblocks = sb->s_maxbytes >> sb->s_blocksize_bits;

> +		/* 1st/root level/node of extents tree stands in i_data and
> +		 * entries stored in tree nodes can be of type ext4_extent
> +		 * (leaf node) or ext4_extent_idx (internal node) */
> +		maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -
> +			      sizeof(struct ext4_extent_header)) /
> +			     max(sizeof(struct ext4_extent),
> +				 sizeof(struct ext4_extent_idx));
> +		/* compute maximum extents tree depth for a fully populated
> +		 * file of max size made of only minimal/1-block extents */
> +		while (maxblocks > 0) {
> +			maxblocks /= (sb->s_blocksize -
> +				      sizeof(struct ext4_extent_header)) /
> +				     max(sizeof(struct ext4_extent),
> +					 sizeof(struct ext4_extent_idx));

These need to be changed to avoid a 64-bit divide, and possibly simplified:

		unsigned ext_size = max(sizeof(struct ext4_extent),
					sizeof(struct ext4_extent_idx));
		unsigned ext_per_leaf = (sb->s_blocksize -
					 sizeof(struct ext4_extent_header)) /
					ext_size);

		do_div(maxblocks,
                       (sizeof(((struct ext4_inode_info *)NULL)->i_data) -
			sizeof(struct ext4_extent_header)) / ext_size);

		while (maxblocks > 0) {
			do_div(maxblocks, ext_per_leaf);
			EXT4_SB(sb)->s_max_ext_tree_depth++;
		}

> +#ifdef EXT_DEBUG
> +		printk(", maximum tree depth=%u",
> +		       EXT4_SB(sb)->s_max_ext_tree_depth);
> #endif
> +		printk("\n");

It isn't great to "continue" printk() statements, since they can get mixed
up if there are multiple messages being printed to the console at once.
Better to calculate the s_max_ext_tree_depth first, then print out the
debugging info in a single printk() call.  Alternately, just make this a
completely separate printk() under EXT_DEBUG instead of trying to continue
the previous one.

Cheers, Andreas

> #ifdef EXTENTS_STATS
> 		spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
> 		EXT4_SB(sb)->s_ext_min = 1 << 30;
> @@ -5348,18 +5383,18 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> 		       ext4_lblk_t start, ext4_lblk_t shift,
> 		       enum SHIFT_DIRECTION SHIFT)
> {
> -	struct ext4_ext_path *path;
> +	struct ext4_ext_path *path, *orig_path;
> 	int ret = 0, depth;
> 	struct ext4_extent *extent;
> 	ext4_lblk_t stop, *iterator, ex_start, ex_end;
> 
> 	/* Let path point to the last extent */
> -	path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);
> -	if (IS_ERR(path))
> -		return PTR_ERR(path);
> +	orig_path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);
> +	if (IS_ERR(orig_path))
> +		return PTR_ERR(orig_path);
> 
> -	depth = path->p_depth;
> -	extent = path[depth].p_ext;
> +	depth = orig_path->p_depth;
> +	extent = orig_path[depth].p_ext;
> 	if (!extent)
> 		goto out;
> 
> @@ -5371,9 +5406,11 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> 	 * sure the hole is big enough to accommodate the shift.
> 	*/
> 	if (SHIFT == SHIFT_LEFT) {
> -		path = ext4_find_extent(inode, start - 1, &path, 0);
> -		if (IS_ERR(path))
> -			return PTR_ERR(path);
> +		path = ext4_find_extent(inode, start - 1, &orig_path, 0);
> +		if (IS_ERR(path)) {
> +			ret = PTR_ERR(path);
> +			goto out;
> +		}
> 		depth = path->p_depth;
> 		extent =  path[depth].p_ext;
> 		if (extent) {
> @@ -5387,9 +5424,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> 
> 		if ((start == ex_start && shift > ex_start) ||
> 		    (shift > start - ex_end)) {
> -			ext4_ext_drop_refs(path);
> -			kfree(path);
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto out;
> 		}
> 	}
> 
> @@ -5405,15 +5441,18 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> 
> 	/* Its safe to start updating extents */
> 	while (start < stop) {
> -		path = ext4_find_extent(inode, *iterator, &path, 0);
> -		if (IS_ERR(path))
> -			return PTR_ERR(path);
> +		path = ext4_find_extent(inode, *iterator, &orig_path, 0);
> +		if (IS_ERR(path)) {
> +			ret = PTR_ERR(path);
> +			goto out;
> +		}
> 		depth = path->p_depth;
> 		extent = path[depth].p_ext;
> 		if (!extent) {
> 			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
> 					 (unsigned long) *iterator);
> -			return -EFSCORRUPTED;
> +			ret =  -EFSCORRUPTED;
> +			goto out;
> 		}
> 		if (SHIFT == SHIFT_LEFT && *iterator >
> 		    le32_to_cpu(extent->ee_block)) {
> @@ -5445,8 +5484,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
> 			break;
> 	}
> out:
> -	ext4_ext_drop_refs(path);
> -	kfree(path);
> +	ext4_ext_drop_refs(orig_path);
> +	kfree(orig_path);
> 	return ret;
> }
> 
> diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
> index fb6f117..7c319c5 100644
> --- a/fs/ext4/move_extent.c
> +++ b/fs/ext4/move_extent.c
> @@ -39,13 +39,11 @@ get_ext_path(struct inode *inode, ext4_lblk_t lblock,
> 	path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE);
> 	if (IS_ERR(path))
> 		return PTR_ERR(path);
> -	if (path[ext_depth(inode)].p_ext == NULL) {
> -		ext4_ext_drop_refs(path);
> -		kfree(path);
> -		*ppath = NULL;
> +	if (path[ext_depth(inode)].p_ext == NULL)
> 		return -ENODATA;
> -	}
> -	*ppath = path;
> +	if (*ppath == NULL)
> +		*ppath = path;
> +	/* XXX else BUG_ON(path != *ppath); */
> 	return 0;
> }
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 486e869..199157a 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3701,6 +3701,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> 		if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
> 			goto failed_mount3a;
> 
> +	ext4_ext_init(sb); /* needed before using extent-mapped journal */
> +
> 	/*
> 	 * The first inode we look at is the journal inode.  Don't try
> 	 * root first: it may be modified in the journal!
> @@ -3894,7 +3896,6 @@ no_journal:
> 		goto failed_mount4a;
> 	}
> 
> -	ext4_ext_init(sb);
> 	err = ext4_mb_init(sb);
> 	if (err) {
> 		ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",
> --


Cheers, Andreas
Faccini, Bruno June 23, 2016, 10:37 a.m. UTC | #5
> Le Jun 16, 2016 à 21:36, Andreas Dilger <adilger@dilger.ca> a écrit :

> 

> On Jun 16, 2016, at 10:53 AM, Faccini, Bruno <bruno.faccini@intel.com> wrote:

>> 

>> From: Bruno Faccini <bruno.faccini@intel.com>

>> 

>> I have first found this way to fix holes in previous ext4 layers versions

>> where an array of struct ext4_ext_path had been allocated with an arbitrary

>> evaluated size and finally could overrun upon ext_depth() growth outside

>> i_data_sem protection. But it seems it can still help with recent ext4

>> version, to avoid re-allocation need and overhead when it can be allocated

>> to max possible extent depth (ie, 5 presently) at first time and for a low

>> cost regarding its memory foot-print, it should also avoid further invalid

>> dereference by underlying callers sharing same ppath (with present

>> inter-routines path re-use scheme), and also upon re-allocation error.

>> 

>> Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>

>> ---

>> fs/ext4/ext4.h        |    3 +

>> fs/ext4/extents.c     |  113 ++++++++++++++++++++++++++--------------

>> fs/ext4/move_extent.c |   10 +--

>> fs/ext4/super.c       |    3 -

>> 4 files changed, 85 insertions(+), 44 deletions(-)

>> 

>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h

>> index 1e20fa9..73d5866 100644

>> --- a/fs/ext4/ext4.h

>> +++ b/fs/ext4/ext4.h

>> @@ -1340,6 +1340,9 @@ struct ext4_sb_info {

>> 	unsigned long s_ext_extents;

>> #endif

>> 

>> +	/* maximum possible extents tree depth, to be computed at mount time */

>> +	unsigned int s_max_ext_tree_depth;

>> +

>> 	/* for buddy allocator */

>> 	struct ext4_group_info ***s_group_info;

>> 	struct inode *s_buddy_cache;

>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c

>> index b52fea3..aee676d 100644

>> --- a/fs/ext4/extents.c

>> +++ b/fs/ext4/extents.c

>> @@ -871,19 +871,18 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,

>> 

>> 	if (path) {

>> 		ext4_ext_drop_refs(path);

>> -		if (depth > path[0].p_maxdepth) {

>> -			kfree(path);

>> -			*orig_path = path = NULL;

>> -		}

>> -	}

>> -	if (!path) {

>> +		/* path has been allocated for the max possible depth

>> +		 * so we can simply reuse it */

>> +		/* XXX need to clear/zero old path content? */

>> +	} else {

>> 		/* account possible depth increase */

>> -		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),

>> +		path = kzalloc(sizeof(struct ext4_ext_path) *

>> +				EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,

>> 				GFP_NOFS);

>> 		if (unlikely(!path))

>> 			return ERR_PTR(-ENOMEM);

>> -		path[0].p_maxdepth = depth + 1;

>> 	}

>> +	path[0].p_maxdepth = depth + 1;

>> 	path[0].p_hdr = eh;

>> 	path[0].p_bh = NULL;

>> 

>> @@ -934,9 +933,11 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,

>> 

>> err:

>> 	ext4_ext_drop_refs(path);

>> -	kfree(path);

>> -	if (orig_path)

>> -		*orig_path = NULL;

>> +

>> +	/* do not free *orig_path, it is likely to be referenced by callers */

>> +	if (!orig_path)

>> +		kfree(path);

>> +

>> 	return ERR_PTR(ret);

>> }

>> 

>> @@ -2147,7 +2148,8 @@ static int ext4_fill_fiemap_extents(struct inode *inode,

>> 				    ext4_lblk_t block, ext4_lblk_t num,

>> 				    struct fiemap_extent_info *fieinfo)

>> {

>> -	struct ext4_ext_path *path = NULL;

>> +	struct ext4_ext_path *path = NULL, *orig_path = NULL;

>> +	struct ext4_ext_path **orig_ppath = &orig_path;

>> 	struct ext4_extent *ex;

>> 	struct extent_status es;

>> 	ext4_lblk_t next, next_del, start = 0, end = 0;

>> @@ -2161,13 +2163,16 @@ static int ext4_fill_fiemap_extents(struct inode *inode,

>> 		/* find extent for this block */

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

>> 

>> -		path = ext4_find_extent(inode, block, &path, 0);

>> +		path = ext4_find_extent(inode, block, orig_ppath, 0);

>> 		if (IS_ERR(path)) {

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

>> 			err = PTR_ERR(path);

>> 			path = NULL;

>> 			break;

>> 		}

>> +		if (!orig_path)

>> +			orig_path = path;

>> +		/* XXX else BUG_ON(path != orig_path); */

>> 

>> 		depth = ext_depth(inode);

>> 		if (unlikely(path[depth].p_hdr == NULL)) {

>> @@ -2287,8 +2292,8 @@ static int ext4_fill_fiemap_extents(struct inode *inode,

>> 		block = es.es_lblk + es.es_len;

>> 	}

>> 

>> -	ext4_ext_drop_refs(path);

>> -	kfree(path);

>> +	ext4_ext_drop_refs(orig_path);

>> +	kfree(orig_path);

>> 	return err;

>> }

>> 

>> @@ -2910,7 +2915,8 @@ again:

>> 			path[k].p_block =

>> 				le16_to_cpu(path[k].p_hdr->eh_entries)+1;

>> 	} else {

>> -		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1),

>> +		path = kzalloc(sizeof(struct ext4_ext_path) *

>> +			       EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,

>> 			       GFP_NOFS);

>> 		if (path == NULL) {

>> 			ext4_journal_stop(handle);

>> @@ -3051,13 +3057,14 @@ out:

>> */

>> void ext4_ext_init(struct super_block *sb)

>> {

>> +	ext4_fsblk_t maxblocks;

>> +

>> 	/*

>> 	 * possible initialization would be here

>> 	 */

>> 

>> 	if (ext4_has_feature_extents(sb)) {

>> -#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)

> 

> This debugging info shouldn't be printed for every mount.  This should be

> kept under the original #ifdef:

> 

> #if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || \

>    defined(EXTENTS_STATS) || defined(EXT_DEBUG)

> 


Ok, I understand, I will try to implement and simplify this in v2 of patch.

> 

>> -		printk(KERN_INFO "EXT4-fs: file extents enabled"

>> +		printk(KERN_INFO "EXT4-fs (%s): file extents enabled"

>> #ifdef AGGRESSIVE_TEST

>> 		       ", aggressive tests"

>> #endif

>> @@ -3067,8 +3074,36 @@ void ext4_ext_init(struct super_block *sb)

>> #ifdef EXTENTS_STATS

>> 		       ", stats"

>> #endif

>> -		       "\n");

>> +		       , sb->s_id);

>> +

>> +

>> +		EXT4_SB(sb)->s_max_ext_tree_depth = 1;

>> +

>> +		maxblocks = sb->s_maxbytes / sb->s_blocksize;

> 

> To avoid the 64-bit divide on 32-bit platforms this can be:

> 

> 		maxblocks = sb->s_maxbytes >> sb->s_blocksize_bits;


Sure, will be in v2 too.

> 

>> +		/* 1st/root level/node of extents tree stands in i_data and

>> +		 * entries stored in tree nodes can be of type ext4_extent

>> +		 * (leaf node) or ext4_extent_idx (internal node) */

>> +		maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -

>> +			      sizeof(struct ext4_extent_header)) /

>> +			     max(sizeof(struct ext4_extent),

>> +				 sizeof(struct ext4_extent_idx));

>> +		/* compute maximum extents tree depth for a fully populated

>> +		 * file of max size made of only minimal/1-block extents */

>> +		while (maxblocks > 0) {

>> +			maxblocks /= (sb->s_blocksize -

>> +				      sizeof(struct ext4_extent_header)) /

>> +				     max(sizeof(struct ext4_extent),

>> +					 sizeof(struct ext4_extent_idx));

> 

> These need to be changed to avoid a 64-bit divide, and possibly simplified:

> 

> 		unsigned ext_size = max(sizeof(struct ext4_extent),

> 					sizeof(struct ext4_extent_idx));

> 		unsigned ext_per_leaf = (sb->s_blocksize -

> 					 sizeof(struct ext4_extent_header)) /

> 					ext_size);

> 

> 		do_div(maxblocks,

>                       (sizeof(((struct ext4_inode_info *)NULL)->i_data) -

> 			sizeof(struct ext4_extent_header)) / ext_size);

> 

> 		while (maxblocks > 0) {

> 			do_div(maxblocks, ext_per_leaf);

> 			EXT4_SB(sb)->s_max_ext_tree_depth++;

> 		}

> 

Will be in v2 too.


>> +#ifdef EXT_DEBUG

>> +		printk(", maximum tree depth=%u",

>> +		       EXT4_SB(sb)->s_max_ext_tree_depth);

>> #endif

>> +		printk("\n");

> 

> It isn't great to "continue" printk() statements, since they can get mixed

> up if there are multiple messages being printed to the console at once.

> Better to calculate the s_max_ext_tree_depth first, then print out the

> debugging info in a single printk() call.  Alternately, just make this a

> completely separate printk() under EXT_DEBUG instead of trying to continue

> the previous one.

> 

Will be in v2 too.

> Cheers, Andreas

> 

>> #ifdef EXTENTS_STATS

>> 		spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);

>> 		EXT4_SB(sb)->s_ext_min = 1 << 30;

>> @@ -5348,18 +5383,18 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,

>> 		       ext4_lblk_t start, ext4_lblk_t shift,

>> 		       enum SHIFT_DIRECTION SHIFT)

>> {

>> -	struct ext4_ext_path *path;

>> +	struct ext4_ext_path *path, *orig_path;

>> 	int ret = 0, depth;

>> 	struct ext4_extent *extent;

>> 	ext4_lblk_t stop, *iterator, ex_start, ex_end;

>> 

>> 	/* Let path point to the last extent */

>> -	path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);

>> -	if (IS_ERR(path))

>> -		return PTR_ERR(path);

>> +	orig_path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);

>> +	if (IS_ERR(orig_path))

>> +		return PTR_ERR(orig_path);

>> 

>> -	depth = path->p_depth;

>> -	extent = path[depth].p_ext;

>> +	depth = orig_path->p_depth;

>> +	extent = orig_path[depth].p_ext;

>> 	if (!extent)

>> 		goto out;

>> 

>> @@ -5371,9 +5406,11 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,

>> 	 * sure the hole is big enough to accommodate the shift.

>> 	*/

>> 	if (SHIFT == SHIFT_LEFT) {

>> -		path = ext4_find_extent(inode, start - 1, &path, 0);

>> -		if (IS_ERR(path))

>> -			return PTR_ERR(path);

>> +		path = ext4_find_extent(inode, start - 1, &orig_path, 0);

>> +		if (IS_ERR(path)) {

>> +			ret = PTR_ERR(path);

>> +			goto out;

>> +		}

>> 		depth = path->p_depth;

>> 		extent =  path[depth].p_ext;

>> 		if (extent) {

>> @@ -5387,9 +5424,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,

>> 

>> 		if ((start == ex_start && shift > ex_start) ||

>> 		    (shift > start - ex_end)) {

>> -			ext4_ext_drop_refs(path);

>> -			kfree(path);

>> -			return -EINVAL;

>> +			ret = -EINVAL;

>> +			goto out;

>> 		}

>> 	}

>> 

>> @@ -5405,15 +5441,18 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,

>> 

>> 	/* Its safe to start updating extents */

>> 	while (start < stop) {

>> -		path = ext4_find_extent(inode, *iterator, &path, 0);

>> -		if (IS_ERR(path))

>> -			return PTR_ERR(path);

>> +		path = ext4_find_extent(inode, *iterator, &orig_path, 0);

>> +		if (IS_ERR(path)) {

>> +			ret = PTR_ERR(path);

>> +			goto out;

>> +		}

>> 		depth = path->p_depth;

>> 		extent = path[depth].p_ext;

>> 		if (!extent) {

>> 			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",

>> 					 (unsigned long) *iterator);

>> -			return -EFSCORRUPTED;

>> +			ret =  -EFSCORRUPTED;

>> +			goto out;

>> 		}

>> 		if (SHIFT == SHIFT_LEFT && *iterator >

>> 		    le32_to_cpu(extent->ee_block)) {

>> @@ -5445,8 +5484,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,

>> 			break;

>> 	}

>> out:

>> -	ext4_ext_drop_refs(path);

>> -	kfree(path);

>> +	ext4_ext_drop_refs(orig_path);

>> +	kfree(orig_path);

>> 	return ret;

>> }

>> 

>> diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c

>> index fb6f117..7c319c5 100644

>> --- a/fs/ext4/move_extent.c

>> +++ b/fs/ext4/move_extent.c

>> @@ -39,13 +39,11 @@ get_ext_path(struct inode *inode, ext4_lblk_t lblock,

>> 	path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE);

>> 	if (IS_ERR(path))

>> 		return PTR_ERR(path);

>> -	if (path[ext_depth(inode)].p_ext == NULL) {

>> -		ext4_ext_drop_refs(path);

>> -		kfree(path);

>> -		*ppath = NULL;

>> +	if (path[ext_depth(inode)].p_ext == NULL)

>> 		return -ENODATA;

>> -	}

>> -	*ppath = path;

>> +	if (*ppath == NULL)

>> +		*ppath = path;

>> +	/* XXX else BUG_ON(path != *ppath); */

>> 	return 0;

>> }

>> 

>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c

>> index 486e869..199157a 100644

>> --- a/fs/ext4/super.c

>> +++ b/fs/ext4/super.c

>> @@ -3701,6 +3701,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)

>> 		if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))

>> 			goto failed_mount3a;

>> 

>> +	ext4_ext_init(sb); /* needed before using extent-mapped journal */

>> +

>> 	/*

>> 	 * The first inode we look at is the journal inode.  Don't try

>> 	 * root first: it may be modified in the journal!

>> @@ -3894,7 +3896,6 @@ no_journal:

>> 		goto failed_mount4a;

>> 	}

>> 

>> -	ext4_ext_init(sb);

>> 	err = ext4_mb_init(sb);

>> 	if (err) {

>> 		ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",

>> --

> 

> 

> Cheers, Andreas

> 

Thanks for your help Andreas.

> 

> 

> 

> 


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diff mbox

Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1e20fa9..73d5866 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1340,6 +1340,9 @@  struct ext4_sb_info {
 	unsigned long s_ext_extents;
 #endif
 
+	/* maximum possible extents tree depth, to be computed at mount time */
+	unsigned int s_max_ext_tree_depth;
+
 	/* for buddy allocator */
 	struct ext4_group_info ***s_group_info;
 	struct inode *s_buddy_cache;
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b52fea3..aee676d 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -871,19 +871,18 @@  ext4_find_extent(struct inode *inode, ext4_lblk_t block,
 
 	if (path) {
 		ext4_ext_drop_refs(path);
-		if (depth > path[0].p_maxdepth) {
-			kfree(path);
-			*orig_path = path = NULL;
-		}
-	}
-	if (!path) {
+		/* path has been allocated for the max possible depth
+		 * so we can simply reuse it */
+		/* XXX need to clear/zero old path content? */
+	} else {
 		/* account possible depth increase */
-		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
+		path = kzalloc(sizeof(struct ext4_ext_path) *
+				EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,
 				GFP_NOFS);
 		if (unlikely(!path))
 			return ERR_PTR(-ENOMEM);
-		path[0].p_maxdepth = depth + 1;
 	}
+	path[0].p_maxdepth = depth + 1;
 	path[0].p_hdr = eh;
 	path[0].p_bh = NULL;
 
@@ -934,9 +933,11 @@  ext4_find_extent(struct inode *inode, ext4_lblk_t block,
 
 err:
 	ext4_ext_drop_refs(path);
-	kfree(path);
-	if (orig_path)
-		*orig_path = NULL;
+
+	/* do not free *orig_path, it is likely to be referenced by callers */
+	if (!orig_path)
+		kfree(path);
+
 	return ERR_PTR(ret);
 }
 
@@ -2147,7 +2148,8 @@  static int ext4_fill_fiemap_extents(struct inode *inode,
 				    ext4_lblk_t block, ext4_lblk_t num,
 				    struct fiemap_extent_info *fieinfo)
 {
-	struct ext4_ext_path *path = NULL;
+	struct ext4_ext_path *path = NULL, *orig_path = NULL;
+	struct ext4_ext_path **orig_ppath = &orig_path;
 	struct ext4_extent *ex;
 	struct extent_status es;
 	ext4_lblk_t next, next_del, start = 0, end = 0;
@@ -2161,13 +2163,16 @@  static int ext4_fill_fiemap_extents(struct inode *inode,
 		/* find extent for this block */
 		down_read(&EXT4_I(inode)->i_data_sem);
 
-		path = ext4_find_extent(inode, block, &path, 0);
+		path = ext4_find_extent(inode, block, orig_ppath, 0);
 		if (IS_ERR(path)) {
 			up_read(&EXT4_I(inode)->i_data_sem);
 			err = PTR_ERR(path);
 			path = NULL;
 			break;
 		}
+		if (!orig_path)
+			orig_path = path;
+		/* XXX else BUG_ON(path != orig_path); */
 
 		depth = ext_depth(inode);
 		if (unlikely(path[depth].p_hdr == NULL)) {
@@ -2287,8 +2292,8 @@  static int ext4_fill_fiemap_extents(struct inode *inode,
 		block = es.es_lblk + es.es_len;
 	}
 
-	ext4_ext_drop_refs(path);
-	kfree(path);
+	ext4_ext_drop_refs(orig_path);
+	kfree(orig_path);
 	return err;
 }
 
@@ -2910,7 +2915,8 @@  again:
 			path[k].p_block =
 				le16_to_cpu(path[k].p_hdr->eh_entries)+1;
 	} else {
-		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1),
+		path = kzalloc(sizeof(struct ext4_ext_path) *
+			       EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,
 			       GFP_NOFS);
 		if (path == NULL) {
 			ext4_journal_stop(handle);
@@ -3051,13 +3057,14 @@  out:
  */
 void ext4_ext_init(struct super_block *sb)
 {
+	ext4_fsblk_t maxblocks;
+
 	/*
 	 * possible initialization would be here
 	 */
 
 	if (ext4_has_feature_extents(sb)) {
-#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
-		printk(KERN_INFO "EXT4-fs: file extents enabled"
+		printk(KERN_INFO "EXT4-fs (%s): file extents enabled"
 #ifdef AGGRESSIVE_TEST
 		       ", aggressive tests"
 #endif
@@ -3067,8 +3074,36 @@  void ext4_ext_init(struct super_block *sb)
 #ifdef EXTENTS_STATS
 		       ", stats"
 #endif
-		       "\n");
+		       , sb->s_id);
+
+
+		EXT4_SB(sb)->s_max_ext_tree_depth = 1;
+
+		maxblocks = sb->s_maxbytes / sb->s_blocksize;
+
+		/* 1st/root level/node of extents tree stands in i_data and
+		 * entries stored in tree nodes can be of type ext4_extent
+		 * (leaf node) or ext4_extent_idx (internal node) */
+		maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -
+			      sizeof(struct ext4_extent_header)) /
+			     max(sizeof(struct ext4_extent),
+				 sizeof(struct ext4_extent_idx));
+
+		/* compute maximum extents tree depth for a fully populated
+		 * file of max size made of only minimal/1-block extents */
+		while (maxblocks > 0) {
+			maxblocks /= (sb->s_blocksize -
+				      sizeof(struct ext4_extent_header)) /
+				     max(sizeof(struct ext4_extent),
+					 sizeof(struct ext4_extent_idx));
+			EXT4_SB(sb)->s_max_ext_tree_depth++;
+		}
+
+#ifdef EXT_DEBUG
+		printk(", maximum tree depth=%u",
+		       EXT4_SB(sb)->s_max_ext_tree_depth);
 #endif
+		printk("\n");
 #ifdef EXTENTS_STATS
 		spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
 		EXT4_SB(sb)->s_ext_min = 1 << 30;
@@ -5348,18 +5383,18 @@  ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 		       ext4_lblk_t start, ext4_lblk_t shift,
 		       enum SHIFT_DIRECTION SHIFT)
 {
-	struct ext4_ext_path *path;
+	struct ext4_ext_path *path, *orig_path;
 	int ret = 0, depth;
 	struct ext4_extent *extent;
 	ext4_lblk_t stop, *iterator, ex_start, ex_end;
 
 	/* Let path point to the last extent */
-	path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);
-	if (IS_ERR(path))
-		return PTR_ERR(path);
+	orig_path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);
+	if (IS_ERR(orig_path))
+		return PTR_ERR(orig_path);
 
-	depth = path->p_depth;
-	extent = path[depth].p_ext;
+	depth = orig_path->p_depth;
+	extent = orig_path[depth].p_ext;
 	if (!extent)
 		goto out;
 
@@ -5371,9 +5406,11 @@  ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 	 * sure the hole is big enough to accommodate the shift.
 	*/
 	if (SHIFT == SHIFT_LEFT) {
-		path = ext4_find_extent(inode, start - 1, &path, 0);
-		if (IS_ERR(path))
-			return PTR_ERR(path);
+		path = ext4_find_extent(inode, start - 1, &orig_path, 0);
+		if (IS_ERR(path)) {
+			ret = PTR_ERR(path);
+			goto out;
+		}
 		depth = path->p_depth;
 		extent =  path[depth].p_ext;
 		if (extent) {
@@ -5387,9 +5424,8 @@  ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 
 		if ((start == ex_start && shift > ex_start) ||
 		    (shift > start - ex_end)) {
-			ext4_ext_drop_refs(path);
-			kfree(path);
-			return -EINVAL;
+			ret = -EINVAL;
+			goto out;
 		}
 	}
 
@@ -5405,15 +5441,18 @@  ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 
 	/* Its safe to start updating extents */
 	while (start < stop) {
-		path = ext4_find_extent(inode, *iterator, &path, 0);
-		if (IS_ERR(path))
-			return PTR_ERR(path);
+		path = ext4_find_extent(inode, *iterator, &orig_path, 0);
+		if (IS_ERR(path)) {
+			ret = PTR_ERR(path);
+			goto out;
+		}
 		depth = path->p_depth;
 		extent = path[depth].p_ext;
 		if (!extent) {
 			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
 					 (unsigned long) *iterator);
-			return -EFSCORRUPTED;
+			ret =  -EFSCORRUPTED;
+			goto out;
 		}
 		if (SHIFT == SHIFT_LEFT && *iterator >
 		    le32_to_cpu(extent->ee_block)) {
@@ -5445,8 +5484,8 @@  ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
 			break;
 	}
 out:
-	ext4_ext_drop_refs(path);
-	kfree(path);
+	ext4_ext_drop_refs(orig_path);
+	kfree(orig_path);
 	return ret;
 }
 
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index fb6f117..7c319c5 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -39,13 +39,11 @@  get_ext_path(struct inode *inode, ext4_lblk_t lblock,
 	path = ext4_find_extent(inode, lblock, ppath, EXT4_EX_NOCACHE);
 	if (IS_ERR(path))
 		return PTR_ERR(path);
-	if (path[ext_depth(inode)].p_ext == NULL) {
-		ext4_ext_drop_refs(path);
-		kfree(path);
-		*ppath = NULL;
+	if (path[ext_depth(inode)].p_ext == NULL)
 		return -ENODATA;
-	}
-	*ppath = path;
+	if (*ppath == NULL)
+		*ppath = path;
+	/* XXX else BUG_ON(path != *ppath); */
 	return 0;
 }
 
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 486e869..199157a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3701,6 +3701,8 @@  static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
 			goto failed_mount3a;
 
+	ext4_ext_init(sb); /* needed before using extent-mapped journal */
+
 	/*
 	 * The first inode we look at is the journal inode.  Don't try
 	 * root first: it may be modified in the journal!
@@ -3894,7 +3896,6 @@  no_journal:
 		goto failed_mount4a;
 	}
 
-	ext4_ext_init(sb);
 	err = ext4_mb_init(sb);
 	if (err) {
 		ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",