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    Subject[PATCH 11/35] whiteout: jffs2 whiteout support
    Date
    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 | 72 +++++++++++++++++++++++++++++++++++++++++++++++-
    fs/jffs2/fs.c | 4 +++
    fs/jffs2/super.c | 2 +-
    include/linux/jffs2.h | 2 +
    4 files changed, 77 insertions(+), 3 deletions(-)

    diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
    index 7aa4417..c259193 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,
    @@ -56,6 +58,7 @@ const struct inode_operations jffs2_dir_inode_operations =
    .mknod = jffs2_mknod,
    .rename = jffs2_rename,
    .check_acl = jffs2_check_acl,
    + .whiteout = jffs2_whiteout,
    .setattr = jffs2_setattr,
    .setxattr = jffs2_setxattr,
    .getxattr = jffs2_getxattr,
    @@ -98,8 +101,14 @@ 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);
    + if (fd->type == DT_WHT)
    + target->d_flags |= DCACHE_WHITEOUT;
    + else
    + ino = fd->ino;
    + spin_unlock(&target->d_lock);
    + }
    mutex_unlock(&dir_f->sem);
    if (ino) {
    inode = jffs2_iget(dir_i->i_sb, ino);
    @@ -498,6 +507,11 @@ 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 +793,60 @@ 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 9a80e8e..c12cd1c 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 */
    --
    1.6.3.3


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