On Fri, 2008-03-21 at 11:48 +0530, Aneesh Kumar K.V wrote: > ext4_ext_get_blocks returns number of blocks allocated with buffer head > 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 and also mark the buffer head unwritten. Some code path tries > to read the block if buffer_head is not new and no uptodate. Marking the buffer > head unwritten avoid this reading. > Seems this patch fixes two bugs together, it would be nice to split to two as they cause two different problems. To fix the bh->b_size warning solof founds for delayed allocation, I would say we need to fix it in ext4_get_blocks_handle() (for indirect files) and ext4_ext_get_blocks()(for extent files) both, not allowing returning b_size greater than what the caller asking for. Also, the patch below seems only address the preallocation map case, we need to fix in in general block lookup case. > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > --- > fs/ext4/extents.c | 14 +++++++++++++- > 1 files changed, 13 insertions(+), 1 deletions(-) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index d6ae40a..edd1bf2 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -2600,8 +2600,20 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, > } > if (create == EXT4_CREATE_UNINITIALIZED_EXT) > 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 return 0 > + */ > + if (allocated > max_blocks) > + allocated = max_blocks; > + /* mark the buffer unwritten */ > + __set_bit(BH_Unwritten, &bh_result->b_state); > goto out2; > + } > > ret = ext4_ext_convert_to_initialized(handle, inode, > path, iblock, -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html