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 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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