Dear all,
I'm reading the code of extents.c, and confused by the function "ext4_ext_punch_hole".
In my understanding, if we want to punch hole for the range (loff_t offset, loff_t length),
then we finally will get one hole block-size aligned, right?
[code in ext4_ext_punch_hole]
first_block = (offset + sb->s_blocksize - 1) >>
EXT4_BLOCK_SIZE_BITS(sb);
stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
[code]
>From the code, we'll get one hole range contained in the range [offset, length+offset-1].
For example, we set the block size to 1K, and we specify the range [offset:1000, offset:2000].
Then we'll get first_block:1,stop_block:2, with some head/tail range ignored.
{-23------|===========|----952---}
1000 1024 2048 2999
offset offset+length-1
'==='means punched hole here.
Please correct me if I'm wrong.
Regards,
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