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-rw-r--r--fs/ext2/dir.c673
1 files changed, 673 insertions, 0 deletions
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
new file mode 100644
index 00000000000..5b5f52876b4
--- /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,
+};
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-27 03:00:28 +0000