[PATCH v2 5/5] fat: permit to return phy block number by fibmap in fallocated region

[PATCH v2 5/5] fat: permit to return phy block number by fibmap in fallocated region

[Namjae Jeon]

From: Namjae Jeon <namjae.jeon@samsung.com>

Make the fibmap call the return the proper physical block number for any
offset request in the fallocated range.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
---
 fs/fat/cache.c |   16 ++++++++++++++--
 fs/fat/inode.c |    4 ++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/fs/fat/cache.c b/fs/fat/cache.c
index c56bd7e..7777822 100644
--- a/fs/fat/cache.c
+++ b/fs/fat/cache.c
@@ -312,6 +312,7 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
 	const unsigned char blocksize_bits = sb->s_blocksize_bits;
 	sector_t last_block;
 	int cluster, offset;
+	loff_t i_size = i_size_read(inode);
 
 	*phys = 0;
 	*mapped_blocks = 0;
@@ -323,10 +324,20 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
 		return 0;
 	}
 
-	last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
+	last_block = (i_size + (blocksize - 1)) >> blocksize_bits;
 	if (sector >= last_block) {
-		if (!create)
+		if (!create) {
+			/*
+			 * to map cluster in case of read request
+			 * for a block in fallocated region
+			 */
+			if (MSDOS_I(inode)->i_disksize >
+			    round_up(i_size, sb->s_blocksize)) {
+				goto out_map_cluster;
+			}
+
 			return 0;
+		}
 
 		/*
 		 * Both ->mmu_private and ->i_disksize can access
@@ -339,6 +350,7 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
 			return 0;
 	}
 
+out_map_cluster:
 	cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
 	offset  = sector & (sbi->sec_per_clus - 1);
 	cluster = fat_bmap_cluster(inode, cluster);
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index c9fb9b6..bdd1efd 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -243,9 +243,9 @@ static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 	sector_t blocknr;
 
 	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
-	down_read(&MSDOS_I(mapping->host)->truncate_lock);
+	mutex_lock(&mapping->host->i_mutex);
 	blocknr = generic_block_bmap(mapping, block, fat_get_block);
-	up_read(&MSDOS_I(mapping->host)->truncate_lock);
+	mutex_unlock(&mapping->host->i_mutex);
 
 	return blocknr;
 }
-- 
1.7.9.5

Re: [PATCH v2 5/5] fat: permit to return phy block number by fibmap in fallocated region

[OGAWA Hirofumi]

Namjae Jeon <linkinjeon@gmail.com> writes:

> diff --git a/fs/fat/cache.c b/fs/fat/cache.c
> index c56bd7e..7777822 100644
> --- a/fs/fat/cache.c
> +++ b/fs/fat/cache.c
> @@ -312,6 +312,7 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
>  	const unsigned char blocksize_bits = sb->s_blocksize_bits;
>  	sector_t last_block;
>  	int cluster, offset;
> +	loff_t i_size = i_size_read(inode);
>  
>  	*phys = 0;
>  	*mapped_blocks = 0;
> @@ -323,10 +324,20 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
>  		return 0;
>  	}
>  
> -	last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
> +	last_block = (i_size + (blocksize - 1)) >> blocksize_bits;
>  	if (sector >= last_block) {
> -		if (!create)
> +		if (!create) {
> +			/*
> +			 * to map cluster in case of read request
> +			 * for a block in fallocated region
> +			 */
> +			if (MSDOS_I(inode)->i_disksize >
> +			    round_up(i_size, sb->s_blocksize)) {
> +				goto out_map_cluster;
> +			}

Said on another reply though, we will have to add new flag for
this. Because normal read get_block() operation should not return
mapping beyond ->i_size.

>  	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
> -	down_read(&MSDOS_I(mapping->host)->truncate_lock);
> +	mutex_lock(&mapping->host->i_mutex);
>  	blocknr = generic_block_bmap(mapping, block, fat_get_block);
> -	up_read(&MSDOS_I(mapping->host)->truncate_lock);
> +	mutex_unlock(&mapping->host->i_mutex);
>  
>  	return blocknr;
>  }

->i_mutex doesn't work for swapfile.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

Re: [PATCH v2 5/5] fat: permit to return phy block number by fibmap in fallocated region

[Namjae Jeon]

2013/12/1, OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>:
> Namjae Jeon <linkinjeon@gmail.com> writes:
>
>> diff --git a/fs/fat/cache.c b/fs/fat/cache.c
>> index c56bd7e..7777822 100644
>> --- a/fs/fat/cache.c
>> +++ b/fs/fat/cache.c
>> @@ -312,6 +312,7 @@ int fat_bmap(struct inode *inode, sector_t sector,
>> sector_t *phys,
>>  	const unsigned char blocksize_bits = sb->s_blocksize_bits;
>>  	sector_t last_block;
>>  	int cluster, offset;
>> +	loff_t i_size = i_size_read(inode);
>>
>>  	*phys = 0;
>>  	*mapped_blocks = 0;
>> @@ -323,10 +324,20 @@ int fat_bmap(struct inode *inode, sector_t sector,
>> sector_t *phys,
>>  		return 0;
>>  	}
>>
>> -	last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
>> +	last_block = (i_size + (blocksize - 1)) >> blocksize_bits;
>>  	if (sector >= last_block) {
>> -		if (!create)
>> +		if (!create) {
>> +			/*
>> +			 * to map cluster in case of read request
>> +			 * for a block in fallocated region
>> +			 */
>> +			if (MSDOS_I(inode)->i_disksize >
>> +			    round_up(i_size, sb->s_blocksize)) {
>> +				goto out_map_cluster;
>> +			}
>
> Said on another reply though, we will have to add new flag for
> this. Because normal read get_block() operation should not return
> mapping beyond ->i_size.
Okay.
>
>>  	/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
>> -	down_read(&MSDOS_I(mapping->host)->truncate_lock);
>> +	mutex_lock(&mapping->host->i_mutex);
>>  	blocknr = generic_block_bmap(mapping, block, fat_get_block);
>> -	up_read(&MSDOS_I(mapping->host)->truncate_lock);
>> +	mutex_unlock(&mapping->host->i_mutex);
>>
>>  	return blocknr;
>>  }
>
> ->i_mutex doesn't work for swapfile.
Sorry, Actually, I don't understand why it is related with swapfile.
Could you elaborate more ?

Thanks.
> --
> OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
>

Re: [PATCH v2 5/5] fat: permit to return phy block number by fibmap in fallocated region

[OGAWA Hirofumi]

Namjae Jeon <linkinjeon@gmail.com> writes:

>> ->i_mutex doesn't work for swapfile.
> Sorry, Actually, I don't understand why it is related with swapfile.
> Could you elaborate more ?

swapfile.c calls ->bmap to know physical address in swapfile. However,
swapfile.c calls ->bmap under inode->i_mutex.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

Re: [PATCH v2 5/5] fat: permit to return phy block number by fibmap in fallocated region

[Namjae Jeon]

2013/12/6, OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>:
> Namjae Jeon <linkinjeon@gmail.com> writes:
>
>>> ->i_mutex doesn't work for swapfile.
>> Sorry, Actually, I don't understand why it is related with swapfile.
>> Could you elaborate more ?
>
> swapfile.c calls ->bmap to know physical address in swapfile. However,
> swapfile.c calls ->bmap under inode->i_mutex.
Okay, Thanks for explanation.

>
> Thanks.
> --
> OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
>