[RFC][PATCH 13/15] ext3 whiteout support

Bharata B Rao
2007-04-17T13:17:14Z

From: Bharata B Rao <bharata@linux.vnet.ibm.com>
Subject: ext3 whiteout support

Introduce whiteout support for ext3.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-bg: Jan Blunck <jblunck@suse.de>
---
fs/ext3/dir.c | 2 -
fs/ext3/namei.c | 65 ++++++++++++++++++++++++++++++++++++++++++++----
fs/ext3/super.c | 11 +++++++-
include/linux/ext3_fs.h | 5 ++-
4 files changed, 75 insertions(+), 8 deletions(-)

--- a/fs/ext3/dir.c
+++ b/fs/ext3/dir.c
@@ -29,7 +29,7 @@
#include <linux/rbtree.h>

static unsigned char ext3_filetype_table[] = {
- DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
+ DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK, DT_WHT
};

static int ext3_readdir(struct file *, void *, filldir_t);
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -1071,6 +1071,7 @@ static unsigned char ext3_type_by_mode[S
[S_IFIFO >> S_SHIFT] = EXT3_FT_FIFO,
[S_IFSOCK >> S_SHIFT] = EXT3_FT_SOCK,
[S_IFLNK >> S_SHIFT] = EXT3_FT_SYMLINK,
+ [S_IFWHT >> S_SHIFT] = EXT3_FT_WHT,
};

static inline void ext3_set_de_type(struct super_block *sb,
@@ -1786,7 +1787,7 @@ out_stop:
/*
* routine to check that the specified directory is empty (for rmdir)
*/
-static int empty_dir (struct inode * inode)
+static int empty_dir (handle_t *handle, struct inode * inode)
{
unsigned long offset;
struct buffer_head * bh;
@@ -1848,8 +1849,28 @@ static int empty_dir (struct inode * ino
continue;
}
if (le32_to_cpu(de->inode)) {
- brelse (bh);
- return 0;
+ /* If this is a whiteout, remove it */
+ if (de->file_type == EXT3_FT_WHT) {
+ unsigned long ino = le32_to_cpu(de->inode);
+ struct inode *tmp_inode = iget(inode->i_sb, ino);
+ if (!tmp_inode) {
+ brelse (bh);
+ return 0;
+ }
+
+ if (ext3_delete_entry(handle, inode, de, bh)) {
+ iput(tmp_inode);
+ brelse (bh);
+ return 0;
+ }
+
+ tmp_inode->i_ctime = inode->i_ctime;
+ tmp_inode->i_nlink--;
+ iput(tmp_inode);
+ } else {
+ brelse (bh);
+ return 0;
+ }
}
offset += le16_to_cpu(de->rec_len);
de = (struct ext3_dir_entry_2 *)
@@ -2031,7 +2052,7 @@ static int ext3_rmdir (struct inode * di
goto end_rmdir;

retval = -ENOTEMPTY;
- if (!empty_dir (inode))
+ if (!empty_dir (handle, inode))
goto end_rmdir;

retval = ext3_delete_entry(handle, dir, de, bh);
@@ -2060,6 +2081,39 @@ end_rmdir:
return retval;
}

+/*
+ * TODO: Not sure about the args to ext3_journal_start. Check.
+ */
+static int ext3_whiteout(struct inode *dir, struct dentry *dentry)
+{
+ struct inode * inode;
+ int err, retries = 0;
+ handle_t *handle;
+
+retry:
+ handle = ext3_journal_start(dir, EXT3_DATA_TRANS_BLOCKS(dir->i_sb) +
+ EXT3_INDEX_EXTRA_TRANS_BLOCKS + 3 +
+ 2*EXT3_QUOTA_INIT_BLOCKS(dir->i_sb));
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ if (IS_DIRSYNC(dir))
+ handle->h_sync = 1;
+
+ inode = ext3_new_inode (handle, dir, S_IFWHT | S_IRUGO);
+ err = PTR_ERR(inode);
+ if (IS_ERR(inode))
+ goto out_stop;
+
+ err = ext3_add_nondir(handle, dentry, inode);
+
+out_stop:
+ ext3_journal_stop(handle);
+ if (err == -ENOSPC && ext3_should_retry_alloc(dir->i_sb, &retries))
+ goto retry;
+ return err;
+}
+
static int ext3_unlink(struct inode * dir, struct dentry *dentry)
{
int retval;
@@ -2261,7 +2315,7 @@ static int ext3_rename (struct inode * o
if (S_ISDIR(old_inode->i_mode)) {
if (new_inode) {
retval = -ENOTEMPTY;
- if (!empty_dir (new_inode))
+ if (!empty_dir (handle, new_inode))
goto end_rename;
}
retval = -EIO;
@@ -2377,6 +2431,7 @@ const struct inode_operations ext3_dir_i
.mkdir = ext3_mkdir,
.rmdir = ext3_rmdir,
.mknod = ext3_mknod,
+ .whiteout = ext3_whiteout,
.rename = ext3_rename,
.setattr = ext3_setattr,
#ifdef CONFIG_EXT3_FS_XATTR
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1493,6 +1493,15 @@ static int ext3_fill_super (struct super
sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
((sbi->s_mount_opt & EXT3_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);

+ if ((sb->s_flags & MS_UNION) && !(sb->s_flags & MS_RDONLY)) {
+ if (!EXT3_HAS_INCOMPAT_FEATURE(sb,
+ EXT3_FEATURE_INCOMPAT_WHITEOUT)) {
+ sb->s_flags |= MS_RDONLY;
+ ext3_warning(sb, __FUNCTION__,
+ "no whiteout support, mounting filesystem read-only");
+ }
+ }
+
if (le32_to_cpu(es->s_rev_level) == EXT3_GOOD_OLD_REV &&
(EXT3_HAS_COMPAT_FEATURE(sb, ~0U) ||
EXT3_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
@@ -2749,7 +2758,7 @@ static struct file_system_type ext3_fs_t
.name = "ext3",
.get_sb = ext3_get_sb,
.kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV,
+ .fs_flags = FS_REQUIRES_DEV | FS_WHT,
};

static int __init init_ext3_fs(void)
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -63,6 +63,7 @@
#define EXT3_UNDEL_DIR_INO 6 /* Undelete directory inode */
#define EXT3_RESIZE_INO 7 /* Reserved group descriptors inode */
#define EXT3_JOURNAL_INO 8 /* Journal inode */
+#define EXT3_WHT_INO 9 /* Whiteout inode */

/* First non-reserved inode for old ext3 filesystems */
#define EXT3_GOOD_OLD_FIRST_INO 11
@@ -582,6 +583,7 @@ static inline int ext3_valid_inum(struct
#define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004 /* Needs recovery */
#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008 /* Journal device */
#define EXT3_FEATURE_INCOMPAT_META_BG 0x0010
+#define EXT3_FEATURE_INCOMPAT_WHITEOUT 0x0020

#define EXT3_FEATURE_COMPAT_SUPP EXT2_FEATURE_COMPAT_EXT_ATTR
#define EXT3_FEATURE_INCOMPAT_SUPP (EXT3_FEATURE_INCOMPAT_FILETYPE| \
@@ -648,8 +650,9 @@ struct ext3_dir_entry_2 {
#define EXT3_FT_FIFO 5
#define EXT3_FT_SOCK 6
#define EXT3_FT_SYMLINK 7
+#define EXT3_FT_WHT 8

-#define EXT3_FT_MAX 8
+#define EXT3_FT_MAX 9

/*
* EXT3_DIR_PAD defines the directory entries boundaries