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authorAndreas Rohner <andreas.rohner@gmx.net>2014-04-03 14:50:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 16:21:25 -0700
commit2cc88f3a5f16ae9a3c8f54de1b2fd4a397b36075 (patch)
treeeccf104b99fbaca714acd78ebe90b574f408f0fe /include
parent00e9ffcd27cc5d0af9076383c6242c32335546f8 (diff)
nilfs2: implementation of NILFS_IOCTL_SET_SUINFO ioctl
With this ioctl the segment usage entries in the SUFILE can be updated from userspace. This is useful, because it allows the userspace GC to modify and update segment usage entries for specific segments, which enables it to avoid unnecessary write operations. If a segment needs to be cleaned, but there is no or very little reclaimable space in it, the cleaning operation basically degrades to a useless moving operation. In the end the only thing that changes is the location of the data and a timestamp in the segment usage information. With this ioctl the GC can skip the cleaning and update the segment usage entries directly instead. This is basically a shortcut to cleaning the segment. It is still necessary to read the segment summary information, but the writing of the live blocks can be skipped if it's not worth it. [konishi.ryusuke@lab.ntt.co.jp: add description of NILFS_IOCTL_SET_SUINFO ioctl] Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/nilfs2_fs.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 252657874a19..1fb465f9baf2 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -905,5 +905,7 @@ struct nilfs_bdesc {
_IOW(NILFS_IOCTL_IDENT, 0x8B, __u64)
#define NILFS_IOCTL_SET_ALLOC_RANGE \
_IOW(NILFS_IOCTL_IDENT, 0x8C, __u64[2])
+#define NILFS_IOCTL_SET_SUINFO \
+ _IOW(NILFS_IOCTL_IDENT, 0x8D, struct nilfs_argv)
#endif /* _LINUX_NILFS_FS_H */