[PATCH v4 4/6] nilfs-utils: add suport for NILFS_IOCTL_SET_SUINFO ioctl

[Andreas Rohner <andreas.rohner-hi6Y0CQ0nG0@public.gmane.org>]

This patch adds library support for the NILFS_IOCTL_SET_SUINFO
ioctl. A new function nilfs_set_suinfo and the structure
nilfs_suinfo_update, which contains the update information, are
added.

With this function the segment usage information can be updated
from userspace, which can be used as a shortcut for certain GC
operations.

Signed-off-by: Andreas Rohner <andreas.rohner-hi6Y0CQ0nG0@public.gmane.org>
---
 include/nilfs.h     |  2 ++
 include/nilfs2_fs.h | 43 +++++++++++++++++++++++++++++++++++++++++++
 lib/nilfs.c         | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+)

diff --git a/include/nilfs.h b/include/nilfs.h
index b5f85d3..da18e24 100644
--- a/include/nilfs.h
+++ b/include/nilfs.h
@@ -304,6 +304,8 @@ int nilfs_delete_checkpoint(struct nilfs *, nilfs_cno_t);
 int nilfs_get_cpstat(const struct nilfs *, struct nilfs_cpstat *);
 ssize_t nilfs_get_suinfo(const struct nilfs *, __u64, struct nilfs_suinfo *,
 			 size_t);
+ssize_t nilfs_set_suinfo(struct nilfs *, struct nilfs_suinfo_update *,
+			 size_t);
 int nilfs_get_sustat(const struct nilfs *, struct nilfs_sustat *);
 ssize_t nilfs_get_vinfo(const struct nilfs *, struct nilfs_vinfo *, size_t);
 ssize_t nilfs_get_bdescs(const struct nilfs *, struct nilfs_bdesc *, size_t);
diff --git a/include/nilfs2_fs.h b/include/nilfs2_fs.h
index e674f44..cf8f633 100644
--- a/include/nilfs2_fs.h
+++ b/include/nilfs2_fs.h
@@ -714,6 +714,47 @@ static inline int nilfs_suinfo_clean(const struct nilfs_suinfo *si)
 }
 
 /* ioctl */
+/**
+ * nilfs_suinfo_update - segment usage information update
+ * @sup_segnum: segment number
+ * @sup_flags: flags for which fields are active in sup_sui
+ * @sup_reserved: reserved necessary for alignment
+ * @sup_sui: segment usage information
+ */
+struct nilfs_suinfo_update {
+	__u64 sup_segnum;
+	__u32 sup_flags;
+	__u32 sup_reserved;
+	struct nilfs_suinfo sup_sui;
+};
+
+enum {
+	NILFS_SUINFO_UPDATE_LASTMOD,
+	NILFS_SUINFO_UPDATE_NBLOCKS,
+	NILFS_SUINFO_UPDATE_FLAGS,
+};
+
+#define NILFS_SUINFO_UPDATE_FNS(flag, name)				\
+static inline void							\
+nilfs_suinfo_update_set_##name(struct nilfs_suinfo_update *sup)		\
+{									\
+	sup->sup_flags |= 1UL << NILFS_SUINFO_UPDATE_##flag;		\
+}									\
+static inline void							\
+nilfs_suinfo_update_clear_##name(struct nilfs_suinfo_update *sup)	\
+{									\
+	sup->sup_flags &= ~(1UL << NILFS_SUINFO_UPDATE_##flag);		\
+}									\
+static inline int							\
+nilfs_suinfo_update_##name(const struct nilfs_suinfo_update *sup)	\
+{									\
+	return !!(sup->sup_flags & (1UL << NILFS_SUINFO_UPDATE_##flag));\
+}
+
+NILFS_SUINFO_UPDATE_FNS(LASTMOD, lastmod)
+NILFS_SUINFO_UPDATE_FNS(NBLOCKS, nblocks)
+NILFS_SUINFO_UPDATE_FNS(FLAGS, flags)
+
 enum {
 	NILFS_CHECKPOINT,
 	NILFS_SNAPSHOT,
@@ -867,5 +908,7 @@ 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 */
diff --git a/lib/nilfs.c b/lib/nilfs.c
index 93822de..e6f7c1e 100644
--- a/lib/nilfs.c
+++ b/lib/nilfs.c
@@ -596,6 +596,41 @@ ssize_t nilfs_get_suinfo(const struct nilfs *nilfs, __u64 segnum,
 }
 
 /**
+ * nilfs_set_suinfo - sets segment usage info
+ * @nilfs: nilfs object
+ * @sup: an array of nilfs_suinfo_update structs
+ * @nsup: number of elements in sup
+ *
+ * Description: Takes an array of nilfs_suinfo_update structs and updates
+ * segment usage info accordingly. Only the fields indicated by sup_flags
+ * are updated.
+ *
+ * Return Value: On success, 0 is returned. On error, -1 is returned.
+ */
+ssize_t nilfs_set_suinfo(struct nilfs *nilfs,
+			 struct nilfs_suinfo_update *sup, size_t nsup)
+{
+	struct nilfs_argv argv;
+
+	if (nilfs->n_iocfd < 0) {
+		errno = EBADF;
+		return -1;
+	}
+
+	argv.v_base = (unsigned long)sup;
+	argv.v_nmembs = nsup;
+	argv.v_size = sizeof(struct nilfs_suinfo_update);
+	argv.v_index = 0;
+	argv.v_flags = 0;
+	if (ioctl(nilfs->n_iocfd, NILFS_IOCTL_SET_SUINFO, &argv) < 0) {
+		if (errno == ENOTTY)
+			nilfs_opt_clear_set_suinfo(nilfs);
+		return -1;
+	}
+	return 0;
+}
+
+/**
  * nilfs_get_sustat - get segment usage statistics
  * @nilfs: nilfs object
  * @sustat: buffer of a nilfs_sustat struct to store statistics in
-- 
1.8.5.3

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