From: NeilBrown <neilb@suse.de>
Date: Fri, 4 Mar 2011 23:44:22 +0000 (+1100)
Subject: accesstime: load delta from atime file and apply when loading inode.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=1eb2efdfa4a54f3f39df0cbaec135c07bdc8fc5e;p=LaFS.git

accesstime: load delta from atime file and apply when loading inode.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/inode.c b/inode.c
index fd8ab77..681b8fe 100644
--- a/inode.c
+++ b/inode.c
@@ -14,6 +14,8 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 
+static void check_atime_ref(struct inode *ino, int async);
+
 /* Supporting an async 'iget' - as required by the cleaner -
  * is slightly non-trivial.
  * iget*_locked will normally wait for any inode with one
@@ -139,8 +141,10 @@ lafs_iget(struct super_block *sb, ino_t inum, int async)
 
 	if (!(ino->i_state & I_NEW)) {
 		putdref(b, MKREF(iget));
-		if (ino->i_mode)
+		if (ino->i_mode) {
+			check_atime_ref(ino, async);
 			return ino;
+		}
 		iput(ino);
 		return ERR_PTR(-ENOENT);
 	}
@@ -185,6 +189,7 @@ lafs_iget(struct super_block *sb, ino_t inum, int async)
 			printk("lafs_import_inode failed %d\n", err);
 		goto err;
 	}
+	check_atime_ref(ino, async);
 	unlock_new_inode(ino);
 out:
 	if (b && test_and_clear_bit(B_Async, &b->b.flags)) {
@@ -389,8 +394,9 @@ lafs_import_inode(struct inode *ino, struct datablock *b)
 		decode_time(&ino->i_mtime, le64_to_cpu(l->modifytime));
 		decode_time(&ino->i_ctime, le64_to_cpu(l->ctime));
 		decode_time(&i->i_accesstime, le64_to_cpu(l->accesstime));
-		ino->i_atime = i->i_accesstime; /* FIXME load from
-						 * accesstime file */
+		ino->i_atime = i->i_accesstime;
+		i->atime_offset = 0; /* Will be filled-in later probably */
+		lafs_add_atime_offset(&ino->i_atime, i->atime_offset);
 		ino->i_size = le64_to_cpu(l->size);
 		i->parent = le32_to_cpu(l->parent);
 		ino->i_nlink = le32_to_cpu(l->linkcount);
@@ -468,6 +474,75 @@ out:
 	return err;
 }
 
+static void check_atime_ref(struct inode *ino, int async)
+{
+	/* If there is an time file in this filesystem the inode
+	 * should hold a reference to the relevant block in
+	 * that file.
+	 */
+	struct inode *root, *at;
+	u32 bnum;
+	struct datablock *b;
+	if (async)
+		/* Never bother for async lookups */
+		return;
+	if (LAFSI(ino)->type < TypeBase)
+		return;
+	if (test_bit(I_AccessTime, &LAFSI(ino)->iflags))
+		return;
+	root = ino_from_sb(ino->i_sb);
+	at = LAFSI(root)->md.fs.accesstime;
+	if (at == NULL)
+		return;
+
+	if (LAFSI(ino)->md.file.atime_offset)
+		LAFSI(ino)->md.file.atime_offset = 0;
+
+	/* "* 2" to get byte number, then shift to get block
+	 * number
+	 */
+	bnum = ino->i_ino >> (at->i_blkbits-1);
+	b = lafs_get_block(at, bnum, NULL, GFP_NOFS, MKREF(atime));
+	if (b) {
+		if (lafs_read_block(b) == 0) {
+			u16 *atp;
+			int i;
+			atp = map_dblock(b);
+			i = (ino->i_ino * 2) & ((1<<at->i_blkbits)-1);
+			LAFSI(ino)->md.file.atime_offset = le16_to_cpu(atp[i]);
+			set_bit(I_AccessTime, &LAFSI(ino)->iflags);
+			unmap_dblock(b, atp);
+			lafs_add_atime_offset(&ino->i_atime,
+					      LAFSI(ino)->md.file.atime_offset);
+		} else
+			putdref(b, MKREF(atime));
+	}
+}
+
+void lafs_add_atime_offset(struct timespec *atime, int offset)
+{
+	int expon;
+	time_t mantissa;
+	if (offset == 0)
+		return;
+
+	expon = offset & 0x1f;
+	if (expon)
+		mantissa = (offset >> 5) | 0x800;
+	else
+		mantissa = (offset >> 5);
+	if (expon >= 11) {
+		/* seconds */
+		mantissa <<= expon-11;
+		atime->tv_sec += mantissa;
+	} else {
+		/* milliseconds */
+		if (expon)
+			mantissa <<= expon-1;
+		timespec_add_ns(atime, (s64)mantissa * 1000000);
+	}
+}
+
 void lafs_inode_checkpin(struct inode *ino)
 {
 	/* Make sure I_Pinned is set correctly.
diff --git a/lafs.h b/lafs.h
index c8c7684..b9b7804 100644
--- a/lafs.h
+++ b/lafs.h
@@ -136,6 +136,7 @@ void lafs_super_write(struct fs *fs, int dev, u64 addr, char *buf, int size);
 int lafs_super_wait(struct fs *fs);
 
 /* inode.c */
+void lafs_add_atime_offset(struct timespec *atime, int offset);
 int __must_check lafs_mount(struct fs *fs);
 struct inode *lafs_iget(struct super_block *fs, ino_t inum, int async);
 struct inode *lafs_iget_fs(struct fs *fs, int fsnum, int inum, int async);
diff --git a/state.h b/state.h
index ecbc996..8f27841 100644
--- a/state.h
+++ b/state.h
@@ -571,6 +571,9 @@ struct lafs_inode {
 #define	I_Pinned 6	/* InoIdx is pinned, i_nlink is non-zero, and consequently
 			 * we own an extra ref to the inode and superblock.
 			 */
+#define I_AccessTime 7	/* Set if this inode holds a reference to the block
+			 * in the accesstime file that holds our atime
+			 */
 /* next three indicate if we hold a reference on the relevant qent */
 #define	I_QUid	8
 #define	I_QGid	9
@@ -617,6 +620,7 @@ struct lafs_inode {
 			u32	table_size;	/* (blocks) */
 		} segmentusage;
 		struct file_md {
+			u16	atime_offset; /* value stored in atime file */
 			u16	flags;
 /*			u16	mode; */
 /*			u32	uid; */