On 01/27/2015 01:37 AM, Dave Chinner wrote:
On Mon, Jan 26, 2015 at 07:14:43PM +0300, Alexander Tsvetkov wrote:
Hello,
I'm trying to understand the expected behaviour of "maxpct" option
in case of small xfs filesystem
comparing the maximum percentage defined for this option with the
percentage of actually allocated
inodes in filesystem, but the result of prepared test case doesn't
correspond to the expectations:
[root@fedora ~]#mkfs.xfs -f -d size=16m -i maxpct=1 /dev/sdb2
On 3.19-rc5, immediately after mount:
# df -i /mnt/scratch
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/ram1 640 3 637 1% /mnt/scratch
Which indicates that imaxpct=1 is being calculated correctly, before
we even look at whether it is being enforced correctly or not.
So, what kernel version?
http://xfs.org/index.php/XFS_FAQ#Q:_What_information_should_I_include_when_reporting_a_problem.3F
I use Fedora20 on vbox virtual machine with latest kernel version available
from fedora repos: 3.17.8-200.fc20.x86_64 and xfsprogs-3.2.1-1.fc20.x86_64.
/dev/sdb test storage is of VDI format, fixed size:
[root@fedora ~]# fdisk -l
Disk /dev/sda: 10.3 GiB, 11005845504 bytes, 21495792 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000011de
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 20469759 9721856 83 Linux
/dev/sda3 20469760 21493759 512000 82 Linux swap / Solaris
Disk /dev/sdb: 8 GiB, 8589934592 bytes, 16777216 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00006ee7
Device Boot Start End Blocks Id System
/dev/sdb1 2048 8390655 4194304 83 Linux
/dev/sdb2 8390656 16777215 4193280 83 Linux
[root@fedora ~]# for i in {0..100000}; do str=$(mktemp
--tmpdir=/mnt/scratch tmp.XXXXXXXXXX); echo $str; done
Which is a complex (and very slow!) way of doing:
# for i in {0..100000}; do echo > /mnt/scratch/$i ; done 2> /dev/null
filesystem is full with created files:
[root@fedora ~]# df -Th | grep scratch
/dev/sdb2 xfs 13M 13M 148K 99% /mnt/scratch
# df -Th /mnt/scratch
Filesystem Type Size Used Avail Use% Mounted on
/dev/ram1 xfs 13M 1.1M 12M 9% /mnt/scratch
# df -i /mnt/scratch
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/ram1 640 640 0 100% /mnt/scratch
and from the number of actually created inodes:
[root@fedora ~]# xfs_db -c "blockget -n" -c "ncheck" /dev/sdb2 | wc -l
40512
That's a directory structure entry count, equivalent to 'find
/mnt/scratch | wc -l', not an allocated inode count which is what
'df -i' reports.
manual page for xfs_db ncheck says about inode numbers not a
directory entry numbers:
"ncheck [-s] [-i ino] Print name-inode pairs"
Even so, on 3.19-rc5:
# xfs_db -c "blockget -n" -c "ncheck" /dev/ram1 | wc -l
637
which matches what 'df -i' tells us about allocated inodes and hence
imaxpct is working as expected.
I have not the same results, just installed 3.19-rc6 and repeated the test,
df -i reports 640 inodes for filesystem, but actually created 40512 files:
[root@fedora ~]# mkfs.xfs -f -d size=16m -i maxpct=1 /dev/sdb2
meta-data=/dev/sdb2 isize=256 agcount=1, agsize=4096 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=4096, imaxpct=1
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@fedora ~]# mount /dev/sdb2 /mnt/scratch/
fill with files until enospc...
[root@fedora ~]# df -i /mnt/scratch/
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sdb2 640 640 0 100% /mnt/scratch
[root@fedora ~]# df -Th /mnt/scratch/
Filesystem Type Size Used Avail Use% Mounted on
/dev/sdb2 xfs 13M 13M 156K 99% /mnt/scratch
[root@fedora ~]# umount /mnt/scratch
[root@fedora ~]# xfs_db -c "blockget -n" -c "ncheck" /dev/sdb2 | wc -l
40512
Looking into ncheck output there are 40512 pairs reported in the output
each with own unique
inode number. ncheck doesn't report inodes count by definition, but what
does these
40512 reported inode numbers mean if only actually 640 inodes were
allocated? From another hand
each new file should have associated meta-data in the corresponding
allocated inode structure, so for
40512 newly created files I expect the same count of allocated inodes,
is it correct?
Cheers,
Dave.
Thanks,
Alexander Tsvetkov
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