From: Valerie Aurora Subject: [PATCH 11/38] whiteout: ext2 whiteout support Date: Tue, 15 Jun 2010 11:39:41 -0700 Message-ID: <1276627208-17242-12-git-send-email-vaurora@redhat.com> References: <1276627208-17242-1-git-send-email-vaurora@redhat.com> Cc: Miklos Szeredi , Jan Blunck , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Valerie Aurora , Theodore Tso , linux-ext4@vger.kernel.org To: Alexander Viro Return-path: In-Reply-To: <1276627208-17242-1-git-send-email-vaurora@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org From: Jan Blunck 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 - Needs serious review. Al wonders: What happens with a delete at the beginning of a block? Will we find the matching dentry or the first empty space? Signed-off-by: Jan Blunck Signed-off-by: Valerie Aurora Cc: Theodore Tso 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