[PATCH 7/9] nilfs2: add additional flags for nilfs_vdesc

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

This patch adds support for additional bit-flags to the
nilfs_vdesc structure used by the GC to communicate block
information from userspace. The field vd_flags cannot be used for
this purpose, because it does not support bit-flags, and changing
that would break backwards compatibility. Therefore the padding
field is renamed to vd_blk_flags to contain more flags.

Unfortunately older versions of the userspace tools do not
initialize the padding field to zero. So it is necessary to signal
to the kernel if the new vd_blk_flags field contains usable flags
or just random data. Since the vd_period field is only used in
userspace, and is guaranteed to contain a value that is > 0
(NILFS_CNO_MIN == 1), it can be used to give the kernel a hint. So
if the userspace tools set vd_period.p_start to 0, the
vd_blk_flags field will be interpreted.

To make the flags available for later stages of the GC process,
they are mapped to corresponding buffer_head flags.

Signed-off-by: Andreas Rohner <andreas.rohner-hi6Y0CQ0nG0@public.gmane.org>
---
 fs/nilfs2/ioctl.c         | 23 ++++++++++++++++---
 fs/nilfs2/page.h          |  6 ++++-
 include/linux/nilfs2_fs.h | 58 +++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 81 insertions(+), 6 deletions(-)

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index f6ee54e..63b1c77 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -578,7 +578,7 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode,
 	struct buffer_head *bh;
 	int ret;
 
-	if (vdesc->vd_flags == 0)
+	if (nilfs_vdesc_data(vdesc))
 		ret = nilfs_gccache_submit_read_data(
 			inode, vdesc->vd_offset, vdesc->vd_blocknr,
 			vdesc->vd_vblocknr, &bh);
@@ -592,7 +592,8 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode,
 			       "%s: invalid virtual block address (%s): "
 			       "ino=%llu, cno=%llu, offset=%llu, "
 			       "blocknr=%llu, vblocknr=%llu\n",
-			       __func__, vdesc->vd_flags ? "node" : "data",
+			       __func__,
+			       nilfs_vdesc_node(vdesc) ? "node" : "data",
 			       (unsigned long long)vdesc->vd_ino,
 			       (unsigned long long)vdesc->vd_cno,
 			       (unsigned long long)vdesc->vd_offset,
@@ -603,7 +604,8 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode,
 	if (unlikely(!list_empty(&bh->b_assoc_buffers))) {
 		printk(KERN_CRIT "%s: conflicting %s buffer: ino=%llu, "
 		       "cno=%llu, offset=%llu, blocknr=%llu, vblocknr=%llu\n",
-		       __func__, vdesc->vd_flags ? "node" : "data",
+		       __func__,
+		       nilfs_vdesc_node(vdesc) ? "node" : "data",
 		       (unsigned long long)vdesc->vd_ino,
 		       (unsigned long long)vdesc->vd_cno,
 		       (unsigned long long)vdesc->vd_offset,
@@ -612,6 +614,12 @@ static int nilfs_ioctl_move_inode_block(struct inode *inode,
 		brelse(bh);
 		return -EEXIST;
 	}
+
+	if (nilfs_vdesc_snapshot(vdesc))
+		set_buffer_nilfs_snapshot(bh);
+	if (nilfs_vdesc_protection_period(vdesc))
+		set_buffer_nilfs_protection_period(bh);
+
 	list_add_tail(&bh->b_assoc_buffers, buffers);
 	return 0;
 }
@@ -662,6 +670,15 @@ static int nilfs_ioctl_move_blocks(struct super_block *sb,
 		}
 
 		do {
+			/*
+			 * old user space tools to not initialize vd_blk_flags
+			 * if vd_period.p_start > 0 then vd_blk_flags was
+			 * not initialized properly and may contain invalid
+			 * flags
+			 */
+			if (vdesc->vd_period.p_start > 0)
+				vdesc->vd_blk_flags = 0;
+
 			ret = nilfs_ioctl_move_inode_block(inode, vdesc,
 							   &buffers);
 			if (unlikely(ret < 0)) {
diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
index a43b828..b9117e6 100644
--- a/fs/nilfs2/page.h
+++ b/fs/nilfs2/page.h
@@ -36,13 +36,17 @@ enum {
 	BH_NILFS_Volatile,
 	BH_NILFS_Checked,
 	BH_NILFS_Redirected,
+	BH_NILFS_Snapshot,
+	BH_NILFS_Protection_Period,
 };
 
 BUFFER_FNS(NILFS_Node, nilfs_node)		/* nilfs node buffers */
 BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
 BUFFER_FNS(NILFS_Checked, nilfs_checked)	/* buffer is verified */
 BUFFER_FNS(NILFS_Redirected, nilfs_redirected)	/* redirected to a copy */
-
+BUFFER_FNS(NILFS_Snapshot, nilfs_snapshot)	/* belongs to a snapshot */
+BUFFER_FNS(NILFS_Protection_Period, nilfs_protection_period) /* protected by
+							protection period */
 
 int __nilfs_clear_page_dirty(struct page *);
 
diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 6ccb2ad..6ffdc09 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -900,7 +900,7 @@ struct nilfs_vinfo {
  * @vd_blocknr: disk block number
  * @vd_offset: logical block offset inside a file
  * @vd_flags: flags (data or node block)
- * @vd_pad: padding
+ * @vd_blk_flags: additional flags
  */
 struct nilfs_vdesc {
 	__u64 vd_ino;
@@ -910,9 +910,63 @@ struct nilfs_vdesc {
 	__u64 vd_blocknr;
 	__u64 vd_offset;
 	__u32 vd_flags;
-	__u32 vd_pad;
+	/*
+	 * vd_blk_flags needed because vd_flags doesn't support
+	 * bit-flags because of backwards compatibility
+	 */
+	__u32 vd_blk_flags;
 };
 
+/* vdesc flags */
+enum {
+	NILFS_VDESC_DATA,
+	NILFS_VDESC_NODE,
+
+	/* ... */
+};
+enum {
+	NILFS_VDESC_SNAPSHOT,
+	NILFS_VDESC_PROTECTION_PERIOD,
+
+	/* ... */
+
+	__NR_NILFS_VDESC_FIELDS,
+};
+
+#define NILFS_VDESC_FNS(flag, name)					\
+static inline void							\
+nilfs_vdesc_set_##name(struct nilfs_vdesc *vdesc)			\
+{									\
+	vdesc->vd_flags = NILFS_VDESC_##flag;				\
+}									\
+static inline int							\
+nilfs_vdesc_##name(const struct nilfs_vdesc *vdesc)			\
+{									\
+	return vdesc->vd_flags == NILFS_VDESC_##flag;			\
+}
+
+#define NILFS_VDESC_FNS2(flag, name)					\
+static inline void							\
+nilfs_vdesc_set_##name(struct nilfs_vdesc *vdesc)			\
+{									\
+	vdesc->vd_blk_flags |= (1UL << NILFS_VDESC_##flag);		\
+}									\
+static inline void							\
+nilfs_vdesc_clear_##name(struct nilfs_vdesc *vdesc)			\
+{									\
+	vdesc->vd_blk_flags &= ~(1UL << NILFS_VDESC_##flag);		\
+}									\
+static inline int							\
+nilfs_vdesc_##name(const struct nilfs_vdesc *vdesc)			\
+{									\
+	return !!(vdesc->vd_blk_flags & (1UL << NILFS_VDESC_##flag));	\
+}
+
+NILFS_VDESC_FNS(DATA, data)
+NILFS_VDESC_FNS(NODE, node)
+NILFS_VDESC_FNS2(SNAPSHOT, snapshot)
+NILFS_VDESC_FNS2(PROTECTION_PERIOD, protection_period)
+
 /**
  * struct nilfs_bdesc - descriptor of disk block number
  * @bd_ino: inode number
-- 
2.3.0

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