lkml.org 
[lkml]   [2010]   [Apr]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 10/35] whiteout: ext2 whiteout support
    Date
    From: Jan Blunck <jblunck@suse.de>

    This patch adds whiteout support to EXT2. A whiteout is an empty directory
    entry (inode == 0) with the file type set to EXT2_FT_WHT. Therefore it
    allocates space in directories. Due to being implemented as a filetype it is
    necessary to have the EXT2_FEATURE_INCOMPAT_FILETYPE flag set.

    XXX - Whiteouts could be implemented as special symbolic links

    Signed-off-by: Jan Blunck <jblunck@suse.de>
    Signed-off-by: Valerie Aurora <vaurora@redhat.com>
    Cc: Theodore Tso <tytso@mit.edu>
    Cc: linux-ext4@vger.kernel.org
    ---
    fs/ext2/dir.c | 96 +++++++++++++++++++++++++++++++++++++++++++++--
    fs/ext2/ext2.h | 3 +
    fs/ext2/inode.c | 11 ++++-
    fs/ext2/namei.c | 67 +++++++++++++++++++++++++++++++-
    fs/ext2/super.c | 6 +++
    include/linux/ext2_fs.h | 4 ++
    6 files changed, 177 insertions(+), 10 deletions(-)

    diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
    index 57207a9..030bd46 100644
    --- a/fs/ext2/dir.c
    +++ b/fs/ext2/dir.c
    @@ -219,7 +219,7 @@ static inline int ext2_match (int len, const char * const name,
    {
    if (len != de->name_len)
    return 0;
    - if (!de->inode)
    + if (!de->inode && (de->file_type != EXT2_FT_WHT))
    return 0;
    return !memcmp(name, de->name, len);
    }
    @@ -255,6 +255,7 @@ static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
    [EXT2_FT_FIFO] = DT_FIFO,
    [EXT2_FT_SOCK] = DT_SOCK,
    [EXT2_FT_SYMLINK] = DT_LNK,
    + [EXT2_FT_WHT] = DT_WHT,
    };

    #define S_SHIFT 12
    @@ -448,6 +449,26 @@ ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child)
    return res;
    }

    +/* Special version for filetype based whiteout support */
    +ino_t ext2_inode_by_dentry(struct inode *dir, struct dentry *dentry)
    +{
    + ino_t res = 0;
    + struct ext2_dir_entry_2 *de;
    + struct page *page;
    +
    + de = ext2_find_entry (dir, &dentry->d_name, &page);
    + if (de) {
    + res = le32_to_cpu(de->inode);
    + if (!res && de->file_type == EXT2_FT_WHT) {
    + spin_lock(&dentry->d_lock);
    + dentry->d_flags |= DCACHE_WHITEOUT;
    + spin_unlock(&dentry->d_lock);
    + }
    + ext2_put_page(page);
    + }
    + return res;
    +}
    +
    /* Releases the page */
    void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
    struct page *page, struct inode *inode, int update_times)
    @@ -523,7 +544,8 @@ static ext2_dirent * ext2_append_entry(struct dentry * dentry,
    goto got_it;
    name_len = EXT2_DIR_REC_LEN(de->name_len);
    rec_len = ext2_rec_len_from_disk(de->rec_len);
    - if (!de->inode && rec_len >= reclen)
    + if (!de->inode && (de->file_type != EXT2_FT_WHT) &&
    + (rec_len >= reclen))
    goto got_it;
    if (rec_len >= name_len + reclen)
    goto got_it;
    @@ -564,8 +586,11 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
    return PTR_ERR(de);

    err = -EEXIST;
    - if (ext2_match (namelen, name, de))
    + if (ext2_match (namelen, name, de)) {
    + if (de->file_type == EXT2_FT_WHT)
    + goto got_it;
    goto out_unlock;
    + }

    got_it:
    name_len = EXT2_DIR_REC_LEN(de->name_len);
    @@ -577,7 +602,8 @@ got_it:
    &page, NULL);
    if (err)
    goto out_unlock;
    - if (de->inode) {
    + if (de->inode || ((de->file_type == EXT2_FT_WHT) &&
    + !ext2_match (namelen, name, de))) {
    ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
    de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
    de->rec_len = ext2_rec_len_to_disk(name_len);
    @@ -646,6 +672,68 @@ out:
    return err;
    }

    +int ext2_whiteout_entry (struct inode * dir, struct dentry * dentry,
    + struct ext2_dir_entry_2 * de, struct page * page)
    +{
    + const char *name = dentry->d_name.name;
    + int namelen = dentry->d_name.len;
    + unsigned short rec_len, name_len;
    + loff_t pos;
    + int err;
    +
    + if (!de) {
    + de = ext2_append_entry(dentry, &page);
    + BUG_ON(!de);
    + }
    +
    + err = -EEXIST;
    + if (ext2_match (namelen, name, de) &&
    + (de->file_type == EXT2_FT_WHT)) {
    + ext2_error(dir->i_sb, __func__,
    + "entry is already a whiteout in directory #%lu",
    + dir->i_ino);
    + goto out_unlock;
    + }
    +
    + name_len = EXT2_DIR_REC_LEN(de->name_len);
    + rec_len = ext2_rec_len_from_disk(de->rec_len);
    +
    + pos = page_offset(page) +
    + (char*)de - (char*)page_address(page);
    + err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
    + &page, NULL);
    + if (err)
    + goto out_unlock;
    + /*
    + * We whiteout an existing entry. Do what ext2_delete_entry() would do,
    + * except that we don't need to merge with the previous entry since
    + * we are going to reuse it.
    + */
    + if (ext2_match (namelen, name, de))
    + de->inode = 0;
    + if (de->inode || (de->file_type == EXT2_FT_WHT)) {
    + ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
    + de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
    + de->rec_len = ext2_rec_len_to_disk(name_len);
    + de = de1;
    + }
    + de->name_len = namelen;
    + memcpy(de->name, name, namelen);
    + de->inode = 0;
    + de->file_type = EXT2_FT_WHT;
    + err = ext2_commit_chunk(page, pos, rec_len);
    + dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
    + EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
    + mark_inode_dirty(dir);
    + /* OFFSET_CACHE */
    +out_put:
    + ext2_put_page(page);
    + return err;
    +out_unlock:
    + unlock_page(page);
    + goto out_put;
    +}
    +
    /*
    * Set the first fragment of directory.
    */
    diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
    index 0b038e4..44d190c 100644
    --- a/fs/ext2/ext2.h
    +++ b/fs/ext2/ext2.h
    @@ -102,9 +102,12 @@ extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_wind
    /* dir.c */
    extern int ext2_add_link (struct dentry *, struct inode *);
    extern ino_t ext2_inode_by_name(struct inode *, struct qstr *);
    +extern ino_t ext2_inode_by_dentry(struct inode *, struct dentry *);
    extern int ext2_make_empty(struct inode *, struct inode *);
    extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,struct qstr *, struct page **);
    extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
    +extern int ext2_whiteout_entry (struct inode *, struct dentry *,
    + struct ext2_dir_entry_2 *, struct page *);
    extern int ext2_empty_dir (struct inode *);
    extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);
    extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, struct inode *, int);
    diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
    index fc13cc1..5ad2cbb 100644
    --- a/fs/ext2/inode.c
    +++ b/fs/ext2/inode.c
    @@ -1184,7 +1184,8 @@ void ext2_set_inode_flags(struct inode *inode)
    {
    unsigned int flags = EXT2_I(inode)->i_flags;

    - inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
    + inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|
    + S_OPAQUE);
    if (flags & EXT2_SYNC_FL)
    inode->i_flags |= S_SYNC;
    if (flags & EXT2_APPEND_FL)
    @@ -1195,6 +1196,8 @@ void ext2_set_inode_flags(struct inode *inode)
    inode->i_flags |= S_NOATIME;
    if (flags & EXT2_DIRSYNC_FL)
    inode->i_flags |= S_DIRSYNC;
    + if (flags & EXT2_OPAQUE_FL)
    + inode->i_flags |= S_OPAQUE;
    }

    /* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
    @@ -1202,8 +1205,8 @@ void ext2_get_inode_flags(struct ext2_inode_info *ei)
    {
    unsigned int flags = ei->vfs_inode.i_flags;

    - ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
    - EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
    + ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|EXT2_IMMUTABLE_FL|
    + EXT2_NOATIME_FL|EXT2_DIRSYNC_FL|EXT2_OPAQUE_FL);
    if (flags & S_SYNC)
    ei->i_flags |= EXT2_SYNC_FL;
    if (flags & S_APPEND)
    @@ -1214,6 +1217,8 @@ void ext2_get_inode_flags(struct ext2_inode_info *ei)
    ei->i_flags |= EXT2_NOATIME_FL;
    if (flags & S_DIRSYNC)
    ei->i_flags |= EXT2_DIRSYNC_FL;
    + if (flags & S_OPAQUE)
    + ei->i_flags |= EXT2_OPAQUE_FL;
    }

    struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
    diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
    index 71efb0e..12195a5 100644
    --- a/fs/ext2/namei.c
    +++ b/fs/ext2/namei.c
    @@ -55,15 +55,16 @@ static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
    * Methods themselves.
    */

    -static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
    +static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry,
    + struct nameidata *nd)
    {
    struct inode * inode;
    ino_t ino;
    -
    +
    if (dentry->d_name.len > EXT2_NAME_LEN)
    return ERR_PTR(-ENAMETOOLONG);

    - ino = ext2_inode_by_name(dir, &dentry->d_name);
    + ino = ext2_inode_by_dentry(dir, dentry);
    inode = NULL;
    if (ino) {
    inode = ext2_iget(dir->i_sb, ino);
    @@ -242,6 +243,10 @@ static int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
    else
    inode->i_mapping->a_ops = &ext2_aops;

    + /* if we call mkdir on a whiteout create an opaque directory */
    + if (dentry->d_flags & DCACHE_WHITEOUT)
    + inode->i_flags |= S_OPAQUE;
    +
    inode_inc_link_count(inode);

    err = ext2_make_empty(inode, dir);
    @@ -307,6 +312,61 @@ static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
    return err;
    }

    +/*
    + * Create a whiteout for the dentry
    + */
    +static int ext2_whiteout(struct inode *dir, struct dentry *dentry,
    + struct dentry *new_dentry)
    +{
    + struct inode * inode = dentry->d_inode;
    + struct ext2_dir_entry_2 * de = NULL;
    + struct page * page;
    + int err = -ENOTEMPTY;
    +
    + if (!EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
    + EXT2_FEATURE_INCOMPAT_FILETYPE)) {
    + ext2_error (dir->i_sb, "ext2_whiteout",
    + "can't set whiteout filetype");
    + err = -EPERM;
    + goto out;
    + }
    +
    + dquot_initialize(dir);
    +
    + if (inode) {
    + if (S_ISDIR(inode->i_mode) && !ext2_empty_dir(inode))
    + goto out;
    +
    + err = -ENOENT;
    + de = ext2_find_entry (dir, &dentry->d_name, &page);
    + if (!de)
    + goto out;
    + lock_page(page);
    + }
    +
    + err = ext2_whiteout_entry (dir, dentry, de, page);
    + if (err)
    + goto out;
    +
    + spin_lock(&new_dentry->d_lock);
    + new_dentry->d_flags |= DCACHE_WHITEOUT;
    + spin_unlock(&new_dentry->d_lock);
    + d_add(new_dentry, NULL);
    +
    + if (inode) {
    + inode->i_ctime = dir->i_ctime;
    + inode_dec_link_count(inode);
    + if (S_ISDIR(inode->i_mode)) {
    + inode->i_size = 0;
    + inode_dec_link_count(inode);
    + inode_dec_link_count(dir);
    + }
    + }
    + err = 0;
    +out:
    + return err;
    +}
    +
    static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
    struct inode * new_dir, struct dentry * new_dentry )
    {
    @@ -409,6 +469,7 @@ const struct inode_operations ext2_dir_inode_operations = {
    .mkdir = ext2_mkdir,
    .rmdir = ext2_rmdir,
    .mknod = ext2_mknod,
    + .whiteout = ext2_whiteout,
    .rename = ext2_rename,
    #ifdef CONFIG_EXT2_FS_XATTR
    .setxattr = generic_setxattr,
    diff --git a/fs/ext2/super.c b/fs/ext2/super.c
    index 42e4a30..000ee17 100644
    --- a/fs/ext2/super.c
    +++ b/fs/ext2/super.c
    @@ -1079,6 +1079,12 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
    if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
    ext2_msg(sb, KERN_WARNING,
    "warning: mounting ext3 filesystem as ext2");
    + /*
    + * Whiteouts (and fallthrus) require explicit whiteout support.
    + */
    + if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_WHITEOUT))
    + sb->s_flags |= MS_WHITEOUT;
    +
    ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
    return 0;

    diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h
    index 2dfa707..20468bd 100644
    --- a/include/linux/ext2_fs.h
    +++ b/include/linux/ext2_fs.h
    @@ -189,6 +189,7 @@ struct ext2_group_desc
    #define EXT2_NOTAIL_FL FS_NOTAIL_FL /* file tail should not be merged */
    #define EXT2_DIRSYNC_FL FS_DIRSYNC_FL /* dirsync behaviour (directories only) */
    #define EXT2_TOPDIR_FL FS_TOPDIR_FL /* Top of directory hierarchies*/
    +#define EXT2_OPAQUE_FL 0x00040000
    #define EXT2_RESERVED_FL FS_RESERVED_FL /* reserved for ext2 lib */

    #define EXT2_FL_USER_VISIBLE FS_FL_USER_VISIBLE /* User visible flags */
    @@ -503,10 +504,12 @@ struct ext2_super_block {
    #define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004
    #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008
    #define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
    +#define EXT2_FEATURE_INCOMPAT_WHITEOUT 0x0020
    #define EXT2_FEATURE_INCOMPAT_ANY 0xffffffff

    #define EXT2_FEATURE_COMPAT_SUPP EXT2_FEATURE_COMPAT_EXT_ATTR
    #define EXT2_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE| \
    + EXT2_FEATURE_INCOMPAT_WHITEOUT| \
    EXT2_FEATURE_INCOMPAT_META_BG)
    #define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
    EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
    @@ -573,6 +576,7 @@ enum {
    EXT2_FT_FIFO = 5,
    EXT2_FT_SOCK = 6,
    EXT2_FT_SYMLINK = 7,
    + EXT2_FT_WHT = 8,
    EXT2_FT_MAX
    };

    --
    1.6.3.3


    \
     
     \ /
      Last update: 2010-04-16 01:15    [W:0.045 / U:59.456 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site