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ext4: make ext4_ext_get_blocks always return <= max_blocks

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ext4_ext_get_blocks() returns number of blocks allocated with buffer
heads unmapped for a read from prealloc space.  This is needed so that
delayed allocation doesn't do block reservation for prealloc space since
the blocks are already resevred on disk.  Fix ext4_ext_get_blocks to not
return greater than max_blocks, since some of the code paths cannot
handle such a return value.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Aneesh Kumar K.V 2008-04-29 08:11:12 -04:00 committed by Theodore Ts'o
parent fd28784adc
commit e067ba0078
1 changed files with 11 additions and 1 deletions
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12
fs/ext4/extents.c
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@ -2570,8 +2570,18 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
} }
if (create == EXT4_CREATE_UNINITIALIZED_EXT) if (create == EXT4_CREATE_UNINITIALIZED_EXT)
goto out; goto out;
if (!create) if (!create) {
/*
* We have blocks reserved already. We
* return allocated blocks so that delalloc
* won't do block reservation for us. But
* the buffer head will be unmapped so that
* a read from the block returns 0s.
*/
if (allocated > max_blocks)
allocated = max_blocks;
goto out2; goto out2;
}
ret = ext4_ext_convert_to_initialized(handle, inode, ret = ext4_ext_convert_to_initialized(handle, inode,
path, iblock, path, iblock,