This new code is a bit more complicated than former ones, the goal is to
show user all statistics required to take a deep insight into filesystem
on how the disk is being fragmentaed.
The goal is achieved by scaning global bitmap from (cluster)group to group
to figure out following factors in the filesystem:
- How many free chunks in a fixed size as user requested.
- How many real free chunks in all size.
- Min/Max/Avg size(in) clusters of free chunks.
- How do free chunks distribute(in size) in terms of a histogram,
just like following:
---------------------------------------------------------
Extent Size Range : Free extents Free Clusters Percent
32K... 64K- : 1 1 0.00%
1M... 2M- : 9 288 0.03%
8M... 16M- : 2 831 0.09%
32M... 64M- : 1 2047 0.23%
128M... 256M- : 1 8191 0.92%
256M... 512M- : 2 21706 2.43%
512M... 1024M- : 27 858623 96.29%
---------------------------------------------------------
Userspace ioctl() call eventually gets the above info returned by passing
a 'struct ocfs2_info_freefrag' with the chunk_size being specified first.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
The new code is dedicated to calculate free inodes number of all inode_allocs,
then return the info to userpace in terms of an array.
Specially, flag 'OCFS2_INFO_FL_NON_COHERENT', manipulated by '--cluster-coherent'
from userspace, is now going to be involved. setting the flag on means no cluster
coherency considered, usually, userspace tools choose none-coherency strategy by
default for the sake of performace.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
We sync our inode flags with ext2 and define them by hex
values. But actually in commit 3669567(4 years ago), all
these values are moved to include/linux/fs.h. So we'd
better also use them as what ext2 did. So sync our inode
flags with ext2 by using FS_*.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
The reason why we need this ioctl is to offer the none-privileged
end-user a possibility to get filesys info gathering.
We use OCFS2_IOC_INFO to manipulate the new ioctl, userspace passes a
structure to kernel containing an array of request pointers and request
count, such as,
* From userspace:
struct ocfs2_info_blocksize oib = {
.ib_req = {
.ir_magic = OCFS2_INFO_MAGIC,
.ir_code = OCFS2_INFO_BLOCKSIZE,
...
}
...
}
struct ocfs2_info_clustersize oic = {
...
}
uint64_t reqs[2] = {(unsigned long)&oib,
(unsigned long)&oic};
struct ocfs2_info info = {
.oi_requests = reqs,
.oi_count = 2,
}
ret = ioctl(fd, OCFS2_IOC_INFO, &info);
* In kernel:
Get the request pointers from *info*, then handle each request one bye one.
Idea here is to make the spearated request small enough to guarantee
a better backward&forward compatibility since a small piece of request
would be less likely to be broken if filesys on raw disk get changed.
Currently, the following 7 requests are supported per the requirement from
userspace tool o2info, and I believe it will grow over time:-)
OCFS2_INFO_CLUSTERSIZE
OCFS2_INFO_BLOCKSIZE
OCFS2_INFO_MAXSLOTS
OCFS2_INFO_LABEL
OCFS2_INFO_UUID
OCFS2_INFO_FS_FEATURES
OCFS2_INFO_JOURNAL_SIZE
This ioctl is only specific to OCFS2.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Currently we were adding ioctl cmds/structures for ocfs2 into ocfs2_fs.h
which was used for define ocfs2 on-disk layout. That sounds a little bit
confusing, and it may be quickly polluted espcially when growing the
ocfs2_info_request ioctls afterwards(it will grow i bet).
As a result, such OCFS2 IOCs do need to be placed somewhere other than
ocfs2_fs.h, a separated ocfs2_ioctl.h will be added to store such ioctl
structures and definitions which could also be used from userspace to
invoke ioctls call.
Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
