Patchwork [16/41] whiteout: jffs2 whiteout support

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Submitter Valerie Aurora Henson
Date Oct. 21, 2009, 7:19 p.m.
Message ID <1256152779-10054-17-git-send-email-vaurora@redhat.com>
Download mbox | patch
Permalink /patch/36619/
State New
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Comments

Valerie Aurora Henson - Oct. 21, 2009, 7:19 p.m.
From: Felix Fietkau <nbd@openwrt.org>

Add support for whiteout dentries to jffs2.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Valerie Aurora <vaurora@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
---
 fs/jffs2/dir.c        |   77 +++++++++++++++++++++++++++++++++++++++++++++++-
 fs/jffs2/fs.c         |    4 ++
 fs/jffs2/super.c      |    2 +-
 include/linux/jffs2.h |    2 +
 4 files changed, 82 insertions(+), 3 deletions(-)
Valerie Aurora Henson - Jan. 26, 2010, 7:52 p.m.
On Mon, Nov 30, 2009 at 02:51:05AM -0500, Erez Zadok wrote:
> In message <1256152779-10054-17-git-send-email-vaurora@redhat.com>, Valerie Aurora writes:
> > From: Felix Fietkau <nbd@openwrt.org>
> > 
> > Add support for whiteout dentries to jffs2.
> > 
> > Signed-off-by: Felix Fietkau <nbd@openwrt.org>
> > Signed-off-by: Valerie Aurora <vaurora@redhat.com>
> > Cc: David Woodhouse <dwmw2@infradead.org>
> > Cc: linux-mtd@lists.infradead.org
> > ---
> >  fs/jffs2/dir.c        |   77 +++++++++++++++++++++++++++++++++++++++++++++++-
> >  fs/jffs2/fs.c         |    4 ++
> >  fs/jffs2/super.c      |    2 +-
> >  include/linux/jffs2.h |    2 +
> >  4 files changed, 82 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
> > index 6f60cc9..46a2e1b 100644
> > --- a/fs/jffs2/dir.c
> > +++ b/fs/jffs2/dir.c
> > @@ -34,6 +34,8 @@ static int jffs2_mknod (struct inode *,struct dentry *,int,dev_t);
> >  static int jffs2_rename (struct inode *, struct dentry *,
> >  			 struct inode *, struct dentry *);
> >  
> > +static int jffs2_whiteout (struct inode *, struct dentry *, struct dentry *);
> > +
> >  const struct file_operations jffs2_dir_operations =
> >  {
> >  	.read =		generic_read_dir,
> > @@ -55,6 +57,7 @@ const struct inode_operations jffs2_dir_inode_operations =
> >  	.rmdir =	jffs2_rmdir,
> >  	.mknod =	jffs2_mknod,
> >  	.rename =	jffs2_rename,
> > +	.whiteout =     jffs2_whiteout,
> >  	.permission =	jffs2_permission,
> >  	.setattr =	jffs2_setattr,
> >  	.setxattr =	jffs2_setxattr,
> > @@ -98,8 +101,18 @@ static struct dentry *jffs2_lookup(struct inode *dir_i, struct dentry *target,
> >  			fd = fd_list;
> >  		}
> >  	}
> > -	if (fd)
> > -		ino = fd->ino;
> > +	if (fd) {
> > +		spin_lock(&target->d_lock);
> > +		switch(fd->type) {
> > +		case DT_WHT:
> > +			target->d_flags |= DCACHE_WHITEOUT;
> > +			break;
> > +		default:
> > +			ino = fd->ino;
> > +			break;
> > +		}
> > +		spin_unlock(&target->d_lock);
> > +	}
> 
> The switch statement above should be simplified into this:
> 
>  if (fd->type == DT_WHT)
> 	target->d_flags |= DCACHE_WHITEOUT;
>  else
> 	ino = fd->ino;

This is because later we add a third case for fallthrus, at which
point a switch statement is easier to read.  But it is confusing and
distracting by itself in this patch, so I changed it as you suggested.


> > +	/* If it's a directory, then check whether it is really empty
> > +	 */
> 
> Format above comment on one line.

Fixxed, thanks.

-VAL

Patch

diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
index 6f60cc9..46a2e1b 100644
--- a/fs/jffs2/dir.c
+++ b/fs/jffs2/dir.c
@@ -34,6 +34,8 @@  static int jffs2_mknod (struct inode *,struct dentry *,int,dev_t);
 static int jffs2_rename (struct inode *, struct dentry *,
 			 struct inode *, struct dentry *);
 
+static int jffs2_whiteout (struct inode *, struct dentry *, struct dentry *);
+
 const struct file_operations jffs2_dir_operations =
 {
 	.read =		generic_read_dir,
@@ -55,6 +57,7 @@  const struct inode_operations jffs2_dir_inode_operations =
 	.rmdir =	jffs2_rmdir,
 	.mknod =	jffs2_mknod,
 	.rename =	jffs2_rename,
+	.whiteout =     jffs2_whiteout,
 	.permission =	jffs2_permission,
 	.setattr =	jffs2_setattr,
 	.setxattr =	jffs2_setxattr,
@@ -98,8 +101,18 @@  static struct dentry *jffs2_lookup(struct inode *dir_i, struct dentry *target,
 			fd = fd_list;
 		}
 	}
-	if (fd)
-		ino = fd->ino;
+	if (fd) {
+		spin_lock(&target->d_lock);
+		switch(fd->type) {
+		case DT_WHT:
+			target->d_flags |= DCACHE_WHITEOUT;
+			break;
+		default:
+			ino = fd->ino;
+			break;
+		}
+		spin_unlock(&target->d_lock);
+	}
 	mutex_unlock(&dir_f->sem);
 	if (ino) {
 		inode = jffs2_iget(dir_i->i_sb, ino);
@@ -498,6 +511,11 @@  static int jffs2_mkdir (struct inode *dir_i, struct dentry *dentry, int mode)
 		return PTR_ERR(inode);
 	}
 
+	if (dentry->d_flags & DCACHE_WHITEOUT) {
+		inode->i_flags |= S_OPAQUE;
+		ri->flags = cpu_to_je16(JFFS2_INO_FLAG_OPAQUE);
+	}
+
 	inode->i_op = &jffs2_dir_inode_operations;
 	inode->i_fop = &jffs2_dir_operations;
 
@@ -779,6 +797,61 @@  static int jffs2_mknod (struct inode *dir_i, struct dentry *dentry, int mode, de
 	return 0;
 }
 
+static int jffs2_whiteout (struct inode *dir, struct dentry *old_dentry,
+			   struct dentry *new_dentry)
+{
+	struct jffs2_sb_info *c = JFFS2_SB_INFO(dir->i_sb);
+	struct jffs2_inode_info *victim_f = NULL;
+	uint32_t now;
+	int ret;
+
+	/* If it's a directory, then check whether it is really empty
+	 */
+	if (new_dentry->d_inode) {
+		victim_f = JFFS2_INODE_INFO(old_dentry->d_inode);
+		if (S_ISDIR(old_dentry->d_inode->i_mode)) {
+			struct jffs2_full_dirent *fd;
+
+			mutex_lock(&victim_f->sem);
+			for (fd = victim_f->dents; fd; fd = fd->next) {
+				if (fd->ino) {
+					mutex_unlock(&victim_f->sem);
+					return -ENOTEMPTY;
+				}
+			}
+			mutex_unlock(&victim_f->sem);
+		}
+	}
+
+	now = get_seconds();
+	ret = jffs2_do_link(c, JFFS2_INODE_INFO(dir), 0, DT_WHT,
+			    new_dentry->d_name.name, new_dentry->d_name.len, now);
+	if (ret)
+		return ret;
+
+	spin_lock(&new_dentry->d_lock);
+	new_dentry->d_flags |= DCACHE_WHITEOUT;
+	spin_unlock(&new_dentry->d_lock);
+	d_add(new_dentry, NULL);
+
+	if (victim_f) {
+		/* There was a victim. Kill it off nicely */
+		drop_nlink(old_dentry->d_inode);
+		/* Don't oops if the victim was a dirent pointing to an
+		   inode which didn't exist. */
+		if (victim_f->inocache) {
+			mutex_lock(&victim_f->sem);
+			if (S_ISDIR(old_dentry->d_inode->i_mode))
+				victim_f->inocache->pino_nlink = 0;
+			else
+				victim_f->inocache->pino_nlink--;
+			mutex_unlock(&victim_f->sem);
+		}
+	}
+
+	return 0;
+}
+
 static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 			 struct inode *new_dir_i, struct dentry *new_dentry)
 {
diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index 3451a81..c1e333c 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -301,6 +301,10 @@  struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
 
 		inode->i_op = &jffs2_dir_inode_operations;
 		inode->i_fop = &jffs2_dir_operations;
+
+		if (je16_to_cpu(latest_node.flags) & JFFS2_INO_FLAG_OPAQUE)
+			inode->i_flags |= S_OPAQUE;
+
 		break;
 	}
 	case S_IFREG:
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 0035c02..6607f0b 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -172,7 +172,7 @@  static int jffs2_fill_super(struct super_block *sb, void *data, int silent)
 
 	sb->s_op = &jffs2_super_operations;
 	sb->s_export_op = &jffs2_export_ops;
-	sb->s_flags = sb->s_flags | MS_NOATIME;
+	sb->s_flags = sb->s_flags | MS_NOATIME | MS_WHITEOUT;
 	sb->s_xattr = jffs2_xattr_handlers;
 #ifdef CONFIG_JFFS2_FS_POSIX_ACL
 	sb->s_flags |= MS_POSIXACL;
diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h
index 2b32d63..65533bb 100644
--- a/include/linux/jffs2.h
+++ b/include/linux/jffs2.h
@@ -87,6 +87,8 @@ 
 #define JFFS2_INO_FLAG_USERCOMPR  2	/* User has requested a specific
 					   compression type */
 
+#define JFFS2_INO_FLAG_OPAQUE     4	/* Directory is opaque (for union mounts) */
+
 
 /* These can go once we've made sure we've caught all uses without
    byteswapping */