[PATCHv3,4/6] ext4: Make ext4_ind_map_blocks work with fiemap
diff mbox series

Message ID 56fc8d3802c578d27d49270600946a0737cef119.1582702694.git.riteshh@linux.ibm.com
State Superseded
Headers show
Series
  • ext4: bmap & fiemap conversion to use iomap
Related show

Commit Message

Ritesh Harjani Feb. 26, 2020, 9:57 a.m. UTC
For indirect block mapping if the i_block > max supported block in inode
then ext4_ind_map_blocks may return a -EIO error. But in case of fiemap
this could be a valid query to ext4_map_blocks.
So in case if !create then return 0. This also makes ext4_warning to
ext4_debug in ext4_block_to_path() for the same reason.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
 fs/ext4/indirect.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Comments

Jan Kara Feb. 26, 2020, 12:39 p.m. UTC | #1
On Wed 26-02-20 15:27:06, Ritesh Harjani wrote:
> For indirect block mapping if the i_block > max supported block in inode
> then ext4_ind_map_blocks may return a -EIO error. But in case of fiemap
> this could be a valid query to ext4_map_blocks.
> So in case if !create then return 0. This also makes ext4_warning to
> ext4_debug in ext4_block_to_path() for the same reason.
> 
> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>

Hmm, won't it be cleaner to just handle this in ext4_iomap_begin_report()?
We do trim map.m_len there anyway so it is only logical to trim it to
proper value supported by the inode on-disk format... BTW, note we have
sbi->s_bitmap_maxbytes value already computed in the superblock...

								Honza

> ---
>  fs/ext4/indirect.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
> index 3a4ab70fe9e0..e1ab495dd900 100644
> --- a/fs/ext4/indirect.c
> +++ b/fs/ext4/indirect.c
> @@ -102,7 +102,11 @@ static int ext4_block_to_path(struct inode *inode,
>  		offsets[n++] = i_block & (ptrs - 1);
>  		final = ptrs;
>  	} else {
> -		ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
> +		/*
> +		 * It's not yet an error to just query beyond max
> +		 * block in inode. Fiemap callers may do so.
> +		 */
> +		ext4_debug("block %lu > max in inode %lu",
>  			     i_block + direct_blocks +
>  			     indirect_blocks + double_blocks, inode->i_ino);
>  	}
> @@ -537,8 +541,11 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
>  	depth = ext4_block_to_path(inode, map->m_lblk, offsets,
>  				   &blocks_to_boundary);
>  
> -	if (depth == 0)
> +	if (depth == 0) {
> +		if (!(flags & EXT4_GET_BLOCKS_CREATE))
> +			err = 0;
>  		goto out;
> +	}
>  
>  	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
>  
> -- 
> 2.21.0
>
Ritesh Harjani Feb. 26, 2020, 12:47 p.m. UTC | #2
On 2/26/20 6:09 PM, Jan Kara wrote:
> On Wed 26-02-20 15:27:06, Ritesh Harjani wrote:
>> For indirect block mapping if the i_block > max supported block in inode
>> then ext4_ind_map_blocks may return a -EIO error. But in case of fiemap
>> this could be a valid query to ext4_map_blocks.
>> So in case if !create then return 0. This also makes ext4_warning to
>> ext4_debug in ext4_block_to_path() for the same reason.
>>
>> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
> 
> Hmm, won't it be cleaner to just handle this in ext4_iomap_begin_report()?
> We do trim map.m_len there anyway so it is only logical to trim it to
> proper value supported by the inode on-disk format... BTW, note we have
> sbi->s_bitmap_maxbytes value already computed in the superblock...

hmm. Yes, thanks for the pointers. Let me check this again.

-ritesh


> 
> 								Honza
> 
>> ---
>>   fs/ext4/indirect.c | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
>> index 3a4ab70fe9e0..e1ab495dd900 100644
>> --- a/fs/ext4/indirect.c
>> +++ b/fs/ext4/indirect.c
>> @@ -102,7 +102,11 @@ static int ext4_block_to_path(struct inode *inode,
>>   		offsets[n++] = i_block & (ptrs - 1);
>>   		final = ptrs;
>>   	} else {
>> -		ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
>> +		/*
>> +		 * It's not yet an error to just query beyond max
>> +		 * block in inode. Fiemap callers may do so.
>> +		 */
>> +		ext4_debug("block %lu > max in inode %lu",
>>   			     i_block + direct_blocks +
>>   			     indirect_blocks + double_blocks, inode->i_ino);
>>   	}
>> @@ -537,8 +541,11 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
>>   	depth = ext4_block_to_path(inode, map->m_lblk, offsets,
>>   				   &blocks_to_boundary);
>>   
>> -	if (depth == 0)
>> +	if (depth == 0) {
>> +		if (!(flags & EXT4_GET_BLOCKS_CREATE))
>> +			err = 0;
>>   		goto out;
>> +	}
>>   
>>   	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
>>   
>> -- 
>> 2.21.0
>>
Darrick J. Wong Feb. 26, 2020, 4:11 p.m. UTC | #3
On Wed, Feb 26, 2020 at 03:27:06PM +0530, Ritesh Harjani wrote:
> For indirect block mapping if the i_block > max supported block in inode
> then ext4_ind_map_blocks may return a -EIO error. But in case of fiemap
> this could be a valid query to ext4_map_blocks.
> So in case if !create then return 0. This also makes ext4_warning to
> ext4_debug in ext4_block_to_path() for the same reason.
> 
> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
> ---
>  fs/ext4/indirect.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
> index 3a4ab70fe9e0..e1ab495dd900 100644
> --- a/fs/ext4/indirect.c
> +++ b/fs/ext4/indirect.c
> @@ -102,7 +102,11 @@ static int ext4_block_to_path(struct inode *inode,
>  		offsets[n++] = i_block & (ptrs - 1);
>  		final = ptrs;
>  	} else {
> -		ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
> +		/*
> +		 * It's not yet an error to just query beyond max
> +		 * block in inode. Fiemap callers may do so.
> +		 */
> +		ext4_debug("block %lu > max in inode %lu",
>  			     i_block + direct_blocks +
>  			     indirect_blocks + double_blocks, inode->i_ino);

Does that mean fiemap callers can spamflood dmesg with this message just
by setting the query start range to a huge value?

--D

>  	}
> @@ -537,8 +541,11 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
>  	depth = ext4_block_to_path(inode, map->m_lblk, offsets,
>  				   &blocks_to_boundary);
>  
> -	if (depth == 0)
> +	if (depth == 0) {
> +		if (!(flags & EXT4_GET_BLOCKS_CREATE))
> +			err = 0;
>  		goto out;
> +	}
>  
>  	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
>  
> -- 
> 2.21.0
>
Ritesh Harjani Feb. 27, 2020, 5:27 a.m. UTC | #4
On 2/26/20 9:41 PM, Darrick J. Wong wrote:
> On Wed, Feb 26, 2020 at 03:27:06PM +0530, Ritesh Harjani wrote:
>> For indirect block mapping if the i_block > max supported block in inode
>> then ext4_ind_map_blocks may return a -EIO error. But in case of fiemap
>> this could be a valid query to ext4_map_blocks.
>> So in case if !create then return 0. This also makes ext4_warning to
>> ext4_debug in ext4_block_to_path() for the same reason.
>>
>> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
>> ---
>>   fs/ext4/indirect.c | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
>> index 3a4ab70fe9e0..e1ab495dd900 100644
>> --- a/fs/ext4/indirect.c
>> +++ b/fs/ext4/indirect.c
>> @@ -102,7 +102,11 @@ static int ext4_block_to_path(struct inode *inode,
>>   		offsets[n++] = i_block & (ptrs - 1);
>>   		final = ptrs;
>>   	} else {
>> -		ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
>> +		/*
>> +		 * It's not yet an error to just query beyond max
>> +		 * block in inode. Fiemap callers may do so.
>> +		 */
>> +		ext4_debug("block %lu > max in inode %lu",
>>   			     i_block + direct_blocks +
>>   			     indirect_blocks + double_blocks, inode->i_ino);
> 
> Does that mean fiemap callers can spamflood dmesg with this message just
> by setting the query start range to a huge value?

Not in the old implementation. But This could happen with indirect
block mapping with new implementation in iomap (as there is no check in 
place before calling ext4_map_blocks()).
Previously __generic_block_fiemap() used to not query beyond
i_size_read(), so we were safe there.

So yes now as Jan also suggested, will add a check in place in
ext4_iomap_begin_report() itself, so that this flooding wont happen.


Thanks for the review!!

-ritesh

> 
> --D
> 
>>   	}
>> @@ -537,8 +541,11 @@ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
>>   	depth = ext4_block_to_path(inode, map->m_lblk, offsets,
>>   				   &blocks_to_boundary);
>>   
>> -	if (depth == 0)
>> +	if (depth == 0) {
>> +		if (!(flags & EXT4_GET_BLOCKS_CREATE))
>> +			err = 0;
>>   		goto out;
>> +	}
>>   
>>   	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
>>   
>> -- 
>> 2.21.0
>>

Patch
diff mbox series

diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 3a4ab70fe9e0..e1ab495dd900 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -102,7 +102,11 @@  static int ext4_block_to_path(struct inode *inode,
 		offsets[n++] = i_block & (ptrs - 1);
 		final = ptrs;
 	} else {
-		ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
+		/*
+		 * It's not yet an error to just query beyond max
+		 * block in inode. Fiemap callers may do so.
+		 */
+		ext4_debug("block %lu > max in inode %lu",
 			     i_block + direct_blocks +
 			     indirect_blocks + double_blocks, inode->i_ino);
 	}
@@ -537,8 +541,11 @@  int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
 	depth = ext4_block_to_path(inode, map->m_lblk, offsets,
 				   &blocks_to_boundary);
 
-	if (depth == 0)
+	if (depth == 0) {
+		if (!(flags & EXT4_GET_BLOCKS_CREATE))
+			err = 0;
 		goto out;
+	}
 
 	partial = ext4_get_branch(inode, depth, offsets, chain, &err);