1 files changed, 673 insertions, 0 deletions

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
new file mode 100644
index 000000000000..5b5f52876b42
--- /dev/null
+++ b/fs/ext2/dir.c
@@ -0,0 +1,673 @@
+/*
+ *  linux/fs/ext2/dir.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/dir.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  ext2 directory handling functions
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ *
+ * All code that works with directory layout had been switched to pagecache
+ * and moved here. AV
+ */
+
+#include "ext2.h"
+#include <linux/pagemap.h>
+#include <linux/smp_lock.h>
+
+typedef struct ext2_dir_entry_2 ext2_dirent;
+
+/*
+ * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
+ * more robust, but we have what we have
+ */
+static inline unsigned ext2_chunk_size(struct inode *inode)
+{
+        return inode->i_sb->s_blocksize;
+}
+
+static inline void ext2_put_page(struct page *page)
+{
+        kunmap(page);
+        page_cache_release(page);
+}
+
+static inline unsigned long dir_pages(struct inode *inode)
+{
+        return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
+}
+
+/*
+ * Return the offset into page `page_nr' of the last valid
+ * byte in that page, plus one.
+ */
+static unsigned
+ext2_last_byte(struct inode *inode, unsigned long page_nr)
+{
+        unsigned last_byte = inode->i_size;
+
+        last_byte -= page_nr << PAGE_CACHE_SHIFT;
+        if (last_byte > PAGE_CACHE_SIZE)
+                last_byte = PAGE_CACHE_SIZE;
+        return last_byte;
+}
+
+static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
+{
+        struct inode *dir = page->mapping->host;
+        int err = 0;
+        dir->i_version++;
+        page->mapping->a_ops->commit_write(NULL, page, from, to);
+        if (IS_DIRSYNC(dir))
+                err = write_one_page(page, 1);
+        else
+                unlock_page(page);
+        return err;
+}
+
+static void ext2_check_page(struct page *page)
+{
+        struct inode *dir = page->mapping->host;
+        struct super_block *sb = dir->i_sb;
+        unsigned chunk_size = ext2_chunk_size(dir);
+        char *kaddr = page_address(page);
+        u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
+        unsigned offs, rec_len;
+        unsigned limit = PAGE_CACHE_SIZE;
+        ext2_dirent *p;
+        char *error;
+
+        if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
+                limit = dir->i_size & ~PAGE_CACHE_MASK;
+                if (limit & (chunk_size - 1))
+                        goto Ebadsize;
+                if (!limit)
+                        goto out;
+        }
+        for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
+                p = (ext2_dirent *)(kaddr + offs);
+                rec_len = le16_to_cpu(p->rec_len);
+
+                if (rec_len < EXT2_DIR_REC_LEN(1))
+                        goto Eshort;
+                if (rec_len & 3)
+                        goto Ealign;
+                if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
+                        goto Enamelen;
+                if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
+                        goto Espan;
+                if (le32_to_cpu(p->inode) > max_inumber)
+                        goto Einumber;
+        }
+        if (offs != limit)
+                goto Eend;
+out:
+        SetPageChecked(page);
+        return;
+
+        /* Too bad, we had an error */
+
+Ebadsize:
+        ext2_error(sb, "ext2_check_page",
+                "size of directory #%lu is not a multiple of chunk size",
+                dir->i_ino
+        );
+        goto fail;
+Eshort:
+        error = "rec_len is smaller than minimal";
+        goto bad_entry;
+Ealign:
+        error = "unaligned directory entry";
+        goto bad_entry;
+Enamelen:
+        error = "rec_len is too small for name_len";
+        goto bad_entry;
+Espan:
+        error = "directory entry across blocks";
+        goto bad_entry;
+Einumber:
+        error = "inode out of bounds";
+bad_entry:
+        ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
+                "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
+                dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
+                (unsigned long) le32_to_cpu(p->inode),
+                rec_len, p->name_len);
+        goto fail;
+Eend:
+        p = (ext2_dirent *)(kaddr + offs);
+        ext2_error (sb, "ext2_check_page",
+                "entry in directory #%lu spans the page boundary"
+                "offset=%lu, inode=%lu",
+                dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
+                (unsigned long) le32_to_cpu(p->inode));
+fail:
+        SetPageChecked(page);
+        SetPageError(page);
+}
+
+static struct page * ext2_get_page(struct inode *dir, unsigned long n)
+{
+        struct address_space *mapping = dir->i_mapping;
+        struct page *page = read_cache_page(mapping, n,
+                                (filler_t*)mapping->a_ops->readpage, NULL);
+        if (!IS_ERR(page)) {
+                wait_on_page_locked(page);
+                kmap(page);
+                if (!PageUptodate(page))
+                        goto fail;
+                if (!PageChecked(page))
+                        ext2_check_page(page);
+                if (PageError(page))
+                        goto fail;
+        }
+        return page;
+
+fail:
+        ext2_put_page(page);
+        return ERR_PTR(-EIO);
+}
+
+/*
+ * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
+ *
+ * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
+ */
+static inline int ext2_match (int len, const char * const name,
+                                        struct ext2_dir_entry_2 * de)
+{
+        if (len != de->name_len)
+                return 0;
+        if (!de->inode)
+                return 0;
+        return !memcmp(name, de->name, len);
+}
+
+/*
+ * p is at least 6 bytes before the end of page
+ */
+static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
+{
+        return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len));
+}
+
+static inline unsigned 
+ext2_validate_entry(char *base, unsigned offset, unsigned mask)
+{
+        ext2_dirent *de = (ext2_dirent*)(base + offset);
+        ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
+        while ((char*)p < (char*)de) {
+                if (p->rec_len == 0)
+                        break;
+                p = ext2_next_entry(p);
+        }
+        return (char *)p - base;
+}
+
+static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
+        [EXT2_FT_UNKNOWN]       = DT_UNKNOWN,
+        [EXT2_FT_REG_FILE]      = DT_REG,
+        [EXT2_FT_DIR]           = DT_DIR,
+        [EXT2_FT_CHRDEV]        = DT_CHR,
+        [EXT2_FT_BLKDEV]        = DT_BLK,
+        [EXT2_FT_FIFO]          = DT_FIFO,
+        [EXT2_FT_SOCK]          = DT_SOCK,
+        [EXT2_FT_SYMLINK]       = DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
+        [S_IFREG >> S_SHIFT]    = EXT2_FT_REG_FILE,
+        [S_IFDIR >> S_SHIFT]    = EXT2_FT_DIR,
+        [S_IFCHR >> S_SHIFT]    = EXT2_FT_CHRDEV,
+        [S_IFBLK >> S_SHIFT]    = EXT2_FT_BLKDEV,
+        [S_IFIFO >> S_SHIFT]    = EXT2_FT_FIFO,
+        [S_IFSOCK >> S_SHIFT]   = EXT2_FT_SOCK,
+        [S_IFLNK >> S_SHIFT]    = EXT2_FT_SYMLINK,
+};
+
+static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
+{
+        mode_t mode = inode->i_mode;
+        if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
+                de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
+        else
+                de->file_type = 0;
+}
+
+static int
+ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
+{
+        loff_t pos = filp->f_pos;
+        struct inode *inode = filp->f_dentry->d_inode;
+        struct super_block *sb = inode->i_sb;
+        unsigned int offset = pos & ~PAGE_CACHE_MASK;
+        unsigned long n = pos >> PAGE_CACHE_SHIFT;
+        unsigned long npages = dir_pages(inode);
+        unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
+        unsigned char *types = NULL;
+        int need_revalidate = (filp->f_version != inode->i_version);
+        int ret;
+
+        if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
+                goto success;
+
+        if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
+                types = ext2_filetype_table;
+
+        for ( ; n < npages; n++, offset = 0) {
+                char *kaddr, *limit;
+                ext2_dirent *de;
+                struct page *page = ext2_get_page(inode, n);
+
+                if (IS_ERR(page)) {
+                        ext2_error(sb, __FUNCTION__,
+                                   "bad page in #%lu",
+                                   inode->i_ino);
+                        filp->f_pos += PAGE_CACHE_SIZE - offset;
+                        ret = -EIO;
+                        goto done;
+                }
+                kaddr = page_address(page);
+                if (need_revalidate) {
+                        offset = ext2_validate_entry(kaddr, offset, chunk_mask);
+                        need_revalidate = 0;
+                }
+                de = (ext2_dirent *)(kaddr+offset);
+                limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
+                for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
+                        if (de->rec_len == 0) {
+                                ext2_error(sb, __FUNCTION__,
+                                        "zero-length directory entry");
+                                ret = -EIO;
+                                ext2_put_page(page);
+                                goto done;
+                        }
+                        if (de->inode) {
+                                int over;
+                                unsigned char d_type = DT_UNKNOWN;
+
+                                if (types && de->file_type < EXT2_FT_MAX)
+                                        d_type = types[de->file_type];
+
+                                offset = (char *)de - kaddr;
+                                over = filldir(dirent, de->name, de->name_len,
+                                                (n<<PAGE_CACHE_SHIFT) | offset,
+                                                le32_to_cpu(de->inode), d_type);
+                                if (over) {
+                                        ext2_put_page(page);
+                                        goto success;
+                                }
+                        }
+                        filp->f_pos += le16_to_cpu(de->rec_len);
+                }
+                ext2_put_page(page);
+        }
+
+success:
+        ret = 0;
+done:
+        filp->f_version = inode->i_version;
+        return ret;
+}
+
+/*
+ *      ext2_find_entry()
+ *
+ * finds an entry in the specified directory with the wanted name. It
+ * returns the page in which the entry was found, and the entry itself
+ * (as a parameter - res_dir). Page is returned mapped and unlocked.
+ * Entry is guaranteed to be valid.
+ */
+struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
+                        struct dentry *dentry, struct page ** res_page)
+{
+        const char *name = dentry->d_name.name;
+        int namelen = dentry->d_name.len;
+        unsigned reclen = EXT2_DIR_REC_LEN(namelen);
+        unsigned long start, n;
+        unsigned long npages = dir_pages(dir);
+        struct page *page = NULL;
+        struct ext2_inode_info *ei = EXT2_I(dir);
+        ext2_dirent * de;
+
+        if (npages == 0)
+                goto out;
+
+        /* OFFSET_CACHE */
+        *res_page = NULL;
+
+        start = ei->i_dir_start_lookup;
+        if (start >= npages)
+                start = 0;
+        n = start;
+        do {
+                char *kaddr;
+                page = ext2_get_page(dir, n);
+                if (!IS_ERR(page)) {
+                        kaddr = page_address(page);
+                        de = (ext2_dirent *) kaddr;
+                        kaddr += ext2_last_byte(dir, n) - reclen;
+                        while ((char *) de <= kaddr) {
+                                if (de->rec_len == 0) {
+                                        ext2_error(dir->i_sb, __FUNCTION__,
+                                                "zero-length directory entry");
+                                        ext2_put_page(page);
+                                        goto out;
+                                }
+                                if (ext2_match (namelen, name, de))
+                                        goto found;
+                                de = ext2_next_entry(de);
+                        }
+                        ext2_put_page(page);
+                }
+                if (++n >= npages)
+                        n = 0;
+        } while (n != start);
+out:
+        return NULL;
+
+found:
+        *res_page = page;
+        ei->i_dir_start_lookup = n;
+        return de;
+}
+
+struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
+{
+        struct page *page = ext2_get_page(dir, 0);
+        ext2_dirent *de = NULL;
+
+        if (!IS_ERR(page)) {
+                de = ext2_next_entry((ext2_dirent *) page_address(page));
+                *p = page;
+        }
+        return de;
+}
+
+ino_t ext2_inode_by_name(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, &page);
+        if (de) {
+                res = le32_to_cpu(de->inode);
+                kunmap(page);
+                page_cache_release(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)
+{
+        unsigned from = (char *) de - (char *) page_address(page);
+        unsigned to = from + le16_to_cpu(de->rec_len);
+        int err;
+
+        lock_page(page);
+        err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
+        if (err)
+                BUG();
+        de->inode = cpu_to_le32(inode->i_ino);
+        ext2_set_de_type (de, inode);
+        err = ext2_commit_chunk(page, from, to);
+        ext2_put_page(page);
+        dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
+        EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
+        mark_inode_dirty(dir);
+}
+
+/*
+ *      Parent is locked.
+ */
+int ext2_add_link (struct dentry *dentry, struct inode *inode)
+{
+        struct inode *dir = dentry->d_parent->d_inode;
+        const char *name = dentry->d_name.name;
+        int namelen = dentry->d_name.len;
+        unsigned chunk_size = ext2_chunk_size(dir);
+        unsigned reclen = EXT2_DIR_REC_LEN(namelen);
+        unsigned short rec_len, name_len;
+        struct page *page = NULL;
+        ext2_dirent * de;
+        unsigned long npages = dir_pages(dir);
+        unsigned long n;
+        char *kaddr;
+        unsigned from, to;
+        int err;
+
+        /*
+         * We take care of directory expansion in the same loop.
+         * This code plays outside i_size, so it locks the page
+         * to protect that region.
+         */
+        for (n = 0; n <= npages; n++) {
+                char *dir_end;
+
+                page = ext2_get_page(dir, n);
+                err = PTR_ERR(page);
+                if (IS_ERR(page))
+                        goto out;
+                lock_page(page);
+                kaddr = page_address(page);
+                dir_end = kaddr + ext2_last_byte(dir, n);
+                de = (ext2_dirent *)kaddr;
+                kaddr += PAGE_CACHE_SIZE - reclen;
+                while ((char *)de <= kaddr) {
+                        if ((char *)de == dir_end) {
+                                /* We hit i_size */
+                                name_len = 0;
+                                rec_len = chunk_size;
+                                de->rec_len = cpu_to_le16(chunk_size);
+                                de->inode = 0;
+                                goto got_it;
+                        }
+                        if (de->rec_len == 0) {
+                                ext2_error(dir->i_sb, __FUNCTION__,
+                                        "zero-length directory entry");
+                                err = -EIO;
+                                goto out_unlock;
+                        }
+                        err = -EEXIST;
+                        if (ext2_match (namelen, name, de))
+                                goto out_unlock;
+                        name_len = EXT2_DIR_REC_LEN(de->name_len);
+                        rec_len = le16_to_cpu(de->rec_len);
+                        if (!de->inode && rec_len >= reclen)
+                                goto got_it;
+                        if (rec_len >= name_len + reclen)
+                                goto got_it;
+                        de = (ext2_dirent *) ((char *) de + rec_len);
+                }
+                unlock_page(page);
+                ext2_put_page(page);
+        }
+        BUG();
+        return -EINVAL;
+
+got_it:
+        from = (char*)de - (char*)page_address(page);
+        to = from + rec_len;
+        err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
+        if (err)
+                goto out_unlock;
+        if (de->inode) {
+                ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
+                de1->rec_len = cpu_to_le16(rec_len - name_len);
+                de->rec_len = cpu_to_le16(name_len);
+                de = de1;
+        }
+        de->name_len = namelen;
+        memcpy (de->name, name, namelen);
+        de->inode = cpu_to_le32(inode->i_ino);
+        ext2_set_de_type (de, inode);
+        err = ext2_commit_chunk(page, from, to);
+        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);
+out:
+        return err;
+out_unlock:
+        unlock_page(page);
+        goto out_put;
+}
+
+/*
+ * ext2_delete_entry deletes a directory entry by merging it with the
+ * previous entry. Page is up-to-date. Releases the page.
+ */
+int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
+{
+        struct address_space *mapping = page->mapping;
+        struct inode *inode = mapping->host;
+        char *kaddr = page_address(page);
+        unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
+        unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len);
+        ext2_dirent * pde = NULL;
+        ext2_dirent * de = (ext2_dirent *) (kaddr + from);
+        int err;
+
+        while ((char*)de < (char*)dir) {
+                if (de->rec_len == 0) {
+                        ext2_error(inode->i_sb, __FUNCTION__,
+                                "zero-length directory entry");
+                        err = -EIO;
+                        goto out;
+                }
+                pde = de;
+                de = ext2_next_entry(de);
+        }
+        if (pde)
+                from = (char*)pde - (char*)page_address(page);
+        lock_page(page);
+        err = mapping->a_ops->prepare_write(NULL, page, from, to);
+        if (err)
+                BUG();
+        if (pde)
+                pde->rec_len = cpu_to_le16(to-from);
+        dir->inode = 0;
+        err = ext2_commit_chunk(page, from, to);
+        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
+        EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
+        mark_inode_dirty(inode);
+out:
+        ext2_put_page(page);
+        return err;
+}
+
+/*
+ * Set the first fragment of directory.
+ */
+int ext2_make_empty(struct inode *inode, struct inode *parent)
+{
+        struct address_space *mapping = inode->i_mapping;
+        struct page *page = grab_cache_page(mapping, 0);
+        unsigned chunk_size = ext2_chunk_size(inode);
+        struct ext2_dir_entry_2 * de;
+        int err;
+        void *kaddr;
+
+        if (!page)
+                return -ENOMEM;
+        err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size);
+        if (err) {
+                unlock_page(page);
+                goto fail;
+        }
+        kaddr = kmap_atomic(page, KM_USER0);
+       memset(kaddr, 0, chunk_size);
+        de = (struct ext2_dir_entry_2 *)kaddr;
+        de->name_len = 1;
+        de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1));
+        memcpy (de->name, ".\0\0", 4);
+        de->inode = cpu_to_le32(inode->i_ino);
+        ext2_set_de_type (de, inode);
+
+        de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
+        de->name_len = 2;
+        de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1));
+        de->inode = cpu_to_le32(parent->i_ino);
+        memcpy (de->name, "..\0", 4);
+        ext2_set_de_type (de, inode);
+        kunmap_atomic(kaddr, KM_USER0);
+        err = ext2_commit_chunk(page, 0, chunk_size);
+fail:
+        page_cache_release(page);
+        return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int ext2_empty_dir (struct inode * inode)
+{
+        struct page *page = NULL;
+        unsigned long i, npages = dir_pages(inode);
+
+        for (i = 0; i < npages; i++) {
+                char *kaddr;
+                ext2_dirent * de;
+                page = ext2_get_page(inode, i);
+
+                if (IS_ERR(page))
+                        continue;
+
+                kaddr = page_address(page);
+                de = (ext2_dirent *)kaddr;
+                kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
+
+                while ((char *)de <= kaddr) {
+                        if (de->rec_len == 0) {
+                                ext2_error(inode->i_sb, __FUNCTION__,
+                                        "zero-length directory entry");
+                                printk("kaddr=%p, de=%p\n", kaddr, de);
+                                goto not_empty;
+                        }
+                        if (de->inode != 0) {
+                                /* check for . and .. */
+                                if (de->name[0] != '.')
+                                        goto not_empty;
+                                if (de->name_len > 2)
+                                        goto not_empty;
+                                if (de->name_len < 2) {
+                                        if (de->inode !=
+                                            cpu_to_le32(inode->i_ino))
+                                                goto not_empty;
+                                } else if (de->name[1] != '.')
+                                        goto not_empty;
+                        }
+                        de = ext2_next_entry(de);
+                }
+                ext2_put_page(page);
+        }
+        return 1;
+
+not_empty:
+        ext2_put_page(page);
+        return 0;
+}
+
+struct file_operations ext2_dir_operations = {
+        .llseek         = generic_file_llseek,
+        .read           = generic_read_dir,
+        .readdir        = ext2_readdir,
+        .ioctl          = ext2_ioctl,
+        .fsync          = ext2_sync_file,
+};