Tsutomu Itoh wrote:
> Hi,
>
> I think that the disk allocation size of each file becomes a monotone increase
> when the file is made.
> But, it sometimes return to 0. Is it correct?
>
The # of blocks is:
stat->blocks = (inode_get_bytes(inode) +
BTRFS_I(inode)->delalloc_bytes) >> 9;
So I think after sub(delalloc_bytes) and before inode_add_bytes(), you may
see 0 value.
>
> The result of the test at 2.6.37-rc4 is shown below.
> (see inode no. 291)
>
> # df -T /test14
> Filesystem Type 1K-blocks Used Available Use% Mounted on
> /dev/sdd14 btrfs 4162560 8736 3709440 1% /test14
> # dd if=/dev/zero of=/test14/dir/as001.26603 bs=1M count=100
> # dd if=/dev/zero of=/test14/dir/as002.26603 bs=1M count=200
> # dd if=/dev/zero of=/test14/dir/sy001.26603 bs=1M count=300 oflag=direct
> # dd if=/dev/zero of=/test14/dir/as003.26603 bs=1M count=400
> # ls -lis /test14/dir
> total 406528
> 288 0 -rw-r--r-- 1 root root 104857600 Dec 7 15:07 as001.26603
> 289 0 -rw-r--r-- 1 root root 209715200 Dec 7 15:07 as002.26603
> -> 291 99328 -rw-r--r-- 1 root root 419430400 Dec 7 15:08 as003.26603
> 290 307200 -rw-r--r-- 1 root root 314572800 Dec 7 15:08 sy001.26603
> # sleep 3
> # ls -lis /test14/dir
> total 406528
> 288 0 -rw-r--r-- 1 root root 104857600 Dec 7 15:07 as001.26603
> 289 0 -rw-r--r-- 1 root root 209715200 Dec 7 15:07 as002.26603
> -> 291 99328 -rw-r--r-- 1 root root 419430400 Dec 7 15:08 as003.26603
> 290 307200 -rw-r--r-- 1 root root 314572800 Dec 7 15:08 sy001.26603
> # sleep 3
> # ls -lis /test14/dir
> total 307200
> 288 0 -rw-r--r-- 1 root root 104857600 Dec 7 15:07 as001.26603
> 289 0 -rw-r--r-- 1 root root 209715200 Dec 7 15:07 as002.26603
> -> 291 0 -rw-r--r-- 1 root root 419430400 Dec 7 15:08 as003.26603
> 290 307200 -rw-r--r-- 1 root root 314572800 Dec 7 15:08 sy001.26603
> # sleep 3
> # ls -lis /test14/dir
> total 409600
> 288 102400 -rw-r--r-- 1 root root 104857600 Dec 7 15:07 as001.26603
> 289 0 -rw-r--r-- 1 root root 209715200 Dec 7 15:07 as002.26603
> -> 291 0 -rw-r--r-- 1 root root 419430400 Dec 7 15:08 as003.26603
> 290 307200 -rw-r--r-- 1 root root 314572800 Dec 7 15:08 sy001.26603
> # sync
> # ls -lis /test14/dir
> total 1024000
> 288 102400 -rw-r--r-- 1 root root 104857600 Dec 7 15:07 as001.26603
> 289 204800 -rw-r--r-- 1 root root 209715200 Dec 7 15:07 as002.26603
> -> 291 409600 -rw-r--r-- 1 root root 419430400 Dec 7 15:08 as003.26603
> 290 307200 -rw-r--r-- 1 root root 314572800 Dec 7 15:08 sy001.26603
>
> The trace result of btrfs_getattr() is shown below.
>
> Dec 7 15:08:03 luna kernel: ino:291 blocks:198656 i_blocks:0 i_bytes:0
> delalloc_bytes:101711872
> Dec 7 15:08:06 luna kernel: ino:291 blocks:198656 i_blocks:0 i_bytes:0
> delalloc_bytes:101711872
> Dec 7 15:08:09 luna kernel: ino:291 blocks:0 i_blocks:0 i_bytes:0
> delalloc_bytes:0
> Dec 7 15:08:12 luna kernel: ino:291 blocks:0 i_blocks:0 i_bytes:0
> delalloc_bytes:0
> Dec 7 15:08:18 luna kernel: ino:291 blocks:819200 i_blocks:819200 i_bytes:0
> delalloc_bytes:0
>
>
> Regards,
> Itoh
>
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