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730 lines
18 KiB
C
730 lines
18 KiB
C
/*
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* linux/fs/ext2/dir.c
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*
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* Copyright (C) 1992, 1993, 1994, 1995
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* Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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*
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* from
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*
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* linux/fs/minix/dir.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext2 directory handling functions
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*
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* Big-endian to little-endian byte-swapping/bitmaps by
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* David S. Miller (davem@caip.rutgers.edu), 1995
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*
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* All code that works with directory layout had been switched to pagecache
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* and moved here. AV
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*/
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#include "ext2.h"
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#include <linux/buffer_head.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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typedef struct ext2_dir_entry_2 ext2_dirent;
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/*
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* Tests against MAX_REC_LEN etc were put in place for 64k block
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* sizes; if that is not possible on this arch, we can skip
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* those tests and speed things up.
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*/
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static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
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{
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unsigned len = le16_to_cpu(dlen);
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#if (PAGE_CACHE_SIZE >= 65536)
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if (len == EXT2_MAX_REC_LEN)
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return 1 << 16;
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#endif
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return len;
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}
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static inline __le16 ext2_rec_len_to_disk(unsigned len)
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{
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#if (PAGE_CACHE_SIZE >= 65536)
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if (len == (1 << 16))
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return cpu_to_le16(EXT2_MAX_REC_LEN);
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else
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BUG_ON(len > (1 << 16));
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#endif
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return cpu_to_le16(len);
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}
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/*
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* ext2 uses block-sized chunks. Arguably, sector-sized ones would be
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* more robust, but we have what we have
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*/
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static inline unsigned ext2_chunk_size(struct inode *inode)
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{
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return inode->i_sb->s_blocksize;
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}
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static inline void ext2_put_page(struct page *page)
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{
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kunmap(page);
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page_cache_release(page);
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}
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static inline unsigned long dir_pages(struct inode *inode)
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{
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return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
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}
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/*
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* Return the offset into page `page_nr' of the last valid
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* byte in that page, plus one.
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*/
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static unsigned
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ext2_last_byte(struct inode *inode, unsigned long page_nr)
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{
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unsigned last_byte = inode->i_size;
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last_byte -= page_nr << PAGE_CACHE_SHIFT;
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if (last_byte > PAGE_CACHE_SIZE)
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last_byte = PAGE_CACHE_SIZE;
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return last_byte;
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}
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static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
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{
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struct address_space *mapping = page->mapping;
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struct inode *dir = mapping->host;
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int err = 0;
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dir->i_version++;
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block_write_end(NULL, mapping, pos, len, len, page, NULL);
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if (pos+len > dir->i_size) {
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i_size_write(dir, pos+len);
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mark_inode_dirty(dir);
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}
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if (IS_DIRSYNC(dir)) {
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err = write_one_page(page, 1);
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if (!err)
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err = sync_inode_metadata(dir, 1);
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} else {
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unlock_page(page);
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}
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return err;
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}
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static void ext2_check_page(struct page *page, int quiet)
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{
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struct inode *dir = page->mapping->host;
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struct super_block *sb = dir->i_sb;
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unsigned chunk_size = ext2_chunk_size(dir);
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char *kaddr = page_address(page);
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u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
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unsigned offs, rec_len;
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unsigned limit = PAGE_CACHE_SIZE;
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ext2_dirent *p;
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char *error;
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if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
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limit = dir->i_size & ~PAGE_CACHE_MASK;
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if (limit & (chunk_size - 1))
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goto Ebadsize;
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if (!limit)
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goto out;
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}
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for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
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p = (ext2_dirent *)(kaddr + offs);
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rec_len = ext2_rec_len_from_disk(p->rec_len);
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if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
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goto Eshort;
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if (unlikely(rec_len & 3))
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goto Ealign;
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if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
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goto Enamelen;
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if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
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goto Espan;
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if (unlikely(le32_to_cpu(p->inode) > max_inumber))
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goto Einumber;
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}
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if (offs != limit)
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goto Eend;
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out:
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SetPageChecked(page);
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return;
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/* Too bad, we had an error */
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Ebadsize:
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if (!quiet)
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ext2_error(sb, __func__,
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"size of directory #%lu is not a multiple "
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"of chunk size", dir->i_ino);
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goto fail;
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Eshort:
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error = "rec_len is smaller than minimal";
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goto bad_entry;
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Ealign:
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error = "unaligned directory entry";
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goto bad_entry;
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Enamelen:
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error = "rec_len is too small for name_len";
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goto bad_entry;
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Espan:
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error = "directory entry across blocks";
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goto bad_entry;
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Einumber:
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error = "inode out of bounds";
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bad_entry:
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if (!quiet)
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ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
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"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
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dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
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(unsigned long) le32_to_cpu(p->inode),
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rec_len, p->name_len);
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goto fail;
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Eend:
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if (!quiet) {
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p = (ext2_dirent *)(kaddr + offs);
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ext2_error(sb, "ext2_check_page",
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"entry in directory #%lu spans the page boundary"
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"offset=%lu, inode=%lu",
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dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
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(unsigned long) le32_to_cpu(p->inode));
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}
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fail:
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SetPageChecked(page);
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SetPageError(page);
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}
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static struct page * ext2_get_page(struct inode *dir, unsigned long n,
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int quiet)
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{
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struct address_space *mapping = dir->i_mapping;
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struct page *page = read_mapping_page(mapping, n, NULL);
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if (!IS_ERR(page)) {
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kmap(page);
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if (!PageChecked(page))
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ext2_check_page(page, quiet);
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if (PageError(page))
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goto fail;
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}
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return page;
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fail:
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ext2_put_page(page);
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return ERR_PTR(-EIO);
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}
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/*
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* NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
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*
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* len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
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*/
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static inline int ext2_match (int len, const char * const name,
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struct ext2_dir_entry_2 * de)
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{
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if (len != de->name_len)
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return 0;
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if (!de->inode)
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return 0;
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return !memcmp(name, de->name, len);
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}
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/*
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* p is at least 6 bytes before the end of page
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*/
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static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
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{
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return (ext2_dirent *)((char *)p +
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ext2_rec_len_from_disk(p->rec_len));
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}
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static inline unsigned
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ext2_validate_entry(char *base, unsigned offset, unsigned mask)
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{
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ext2_dirent *de = (ext2_dirent*)(base + offset);
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ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
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while ((char*)p < (char*)de) {
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if (p->rec_len == 0)
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break;
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p = ext2_next_entry(p);
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}
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return (char *)p - base;
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}
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static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
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[EXT2_FT_UNKNOWN] = DT_UNKNOWN,
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[EXT2_FT_REG_FILE] = DT_REG,
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[EXT2_FT_DIR] = DT_DIR,
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[EXT2_FT_CHRDEV] = DT_CHR,
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[EXT2_FT_BLKDEV] = DT_BLK,
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[EXT2_FT_FIFO] = DT_FIFO,
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[EXT2_FT_SOCK] = DT_SOCK,
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[EXT2_FT_SYMLINK] = DT_LNK,
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};
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#define S_SHIFT 12
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static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
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[S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
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[S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
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[S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
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[S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
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[S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
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[S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
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[S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
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};
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static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
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{
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umode_t mode = inode->i_mode;
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if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
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de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
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else
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de->file_type = 0;
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}
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static int
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ext2_readdir(struct file *file, struct dir_context *ctx)
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{
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loff_t pos = ctx->pos;
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struct inode *inode = file_inode(file);
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struct super_block *sb = inode->i_sb;
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unsigned int offset = pos & ~PAGE_CACHE_MASK;
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unsigned long n = pos >> PAGE_CACHE_SHIFT;
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unsigned long npages = dir_pages(inode);
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unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
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unsigned char *types = NULL;
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int need_revalidate = file->f_version != inode->i_version;
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if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
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return 0;
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if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
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types = ext2_filetype_table;
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for ( ; n < npages; n++, offset = 0) {
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char *kaddr, *limit;
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ext2_dirent *de;
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struct page *page = ext2_get_page(inode, n, 0);
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if (IS_ERR(page)) {
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ext2_error(sb, __func__,
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"bad page in #%lu",
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inode->i_ino);
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ctx->pos += PAGE_CACHE_SIZE - offset;
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return PTR_ERR(page);
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}
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kaddr = page_address(page);
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if (unlikely(need_revalidate)) {
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if (offset) {
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offset = ext2_validate_entry(kaddr, offset, chunk_mask);
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ctx->pos = (n<<PAGE_CACHE_SHIFT) + offset;
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}
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file->f_version = inode->i_version;
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need_revalidate = 0;
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}
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de = (ext2_dirent *)(kaddr+offset);
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limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
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for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
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if (de->rec_len == 0) {
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ext2_error(sb, __func__,
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"zero-length directory entry");
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ext2_put_page(page);
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return -EIO;
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}
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if (de->inode) {
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unsigned char d_type = DT_UNKNOWN;
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if (types && de->file_type < EXT2_FT_MAX)
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d_type = types[de->file_type];
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if (!dir_emit(ctx, de->name, de->name_len,
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le32_to_cpu(de->inode),
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d_type)) {
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ext2_put_page(page);
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return 0;
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}
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}
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ctx->pos += ext2_rec_len_from_disk(de->rec_len);
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}
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ext2_put_page(page);
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}
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return 0;
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}
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/*
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* ext2_find_entry()
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*
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* finds an entry in the specified directory with the wanted name. It
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* returns the page in which the entry was found (as a parameter - res_page),
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* and the entry itself. Page is returned mapped and unlocked.
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* Entry is guaranteed to be valid.
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*/
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struct ext2_dir_entry_2 *ext2_find_entry (struct inode * dir,
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struct qstr *child, struct page ** res_page)
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{
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const char *name = child->name;
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int namelen = child->len;
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unsigned reclen = EXT2_DIR_REC_LEN(namelen);
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unsigned long start, n;
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unsigned long npages = dir_pages(dir);
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struct page *page = NULL;
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struct ext2_inode_info *ei = EXT2_I(dir);
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ext2_dirent * de;
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int dir_has_error = 0;
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if (npages == 0)
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goto out;
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/* OFFSET_CACHE */
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*res_page = NULL;
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start = ei->i_dir_start_lookup;
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if (start >= npages)
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start = 0;
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n = start;
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do {
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char *kaddr;
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page = ext2_get_page(dir, n, dir_has_error);
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if (!IS_ERR(page)) {
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kaddr = page_address(page);
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de = (ext2_dirent *) kaddr;
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kaddr += ext2_last_byte(dir, n) - reclen;
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while ((char *) de <= kaddr) {
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if (de->rec_len == 0) {
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ext2_error(dir->i_sb, __func__,
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"zero-length directory entry");
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ext2_put_page(page);
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goto out;
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}
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if (ext2_match (namelen, name, de))
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goto found;
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de = ext2_next_entry(de);
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}
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ext2_put_page(page);
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} else
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dir_has_error = 1;
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if (++n >= npages)
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n = 0;
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/* next page is past the blocks we've got */
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if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
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ext2_error(dir->i_sb, __func__,
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"dir %lu size %lld exceeds block count %llu",
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dir->i_ino, dir->i_size,
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(unsigned long long)dir->i_blocks);
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goto out;
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}
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} while (n != start);
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out:
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return NULL;
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found:
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*res_page = page;
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ei->i_dir_start_lookup = n;
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return de;
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}
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struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
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{
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struct page *page = ext2_get_page(dir, 0, 0);
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ext2_dirent *de = NULL;
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if (!IS_ERR(page)) {
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de = ext2_next_entry((ext2_dirent *) page_address(page));
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*p = page;
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}
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return de;
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}
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ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child)
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{
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ino_t res = 0;
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struct ext2_dir_entry_2 *de;
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struct page *page;
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de = ext2_find_entry (dir, child, &page);
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if (de) {
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res = le32_to_cpu(de->inode);
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ext2_put_page(page);
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}
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return res;
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}
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static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
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{
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return __block_write_begin(page, pos, len, ext2_get_block);
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}
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/* Releases the page */
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void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
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struct page *page, struct inode *inode, int update_times)
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{
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loff_t pos = page_offset(page) +
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(char *) de - (char *) page_address(page);
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unsigned len = ext2_rec_len_from_disk(de->rec_len);
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int err;
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lock_page(page);
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err = ext2_prepare_chunk(page, pos, len);
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BUG_ON(err);
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de->inode = cpu_to_le32(inode->i_ino);
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ext2_set_de_type(de, inode);
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err = ext2_commit_chunk(page, pos, len);
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ext2_put_page(page);
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if (update_times)
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dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
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EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
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mark_inode_dirty(dir);
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}
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/*
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* Parent is locked.
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*/
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int ext2_add_link (struct dentry *dentry, struct inode *inode)
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{
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struct inode *dir = dentry->d_parent->d_inode;
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const char *name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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unsigned chunk_size = ext2_chunk_size(dir);
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unsigned reclen = EXT2_DIR_REC_LEN(namelen);
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unsigned short rec_len, name_len;
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struct page *page = NULL;
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ext2_dirent * de;
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unsigned long npages = dir_pages(dir);
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unsigned long n;
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char *kaddr;
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loff_t pos;
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int err;
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|
|
/*
|
|
* 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, 0);
|
|
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 = ext2_rec_len_to_disk(chunk_size);
|
|
de->inode = 0;
|
|
goto got_it;
|
|
}
|
|
if (de->rec_len == 0) {
|
|
ext2_error(dir->i_sb, __func__,
|
|
"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 = ext2_rec_len_from_disk(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:
|
|
pos = page_offset(page) +
|
|
(char*)de - (char*)page_address(page);
|
|
err = ext2_prepare_chunk(page, pos, rec_len);
|
|
if (err)
|
|
goto out_unlock;
|
|
if (de->inode) {
|
|
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 = cpu_to_le32(inode->i_ino);
|
|
ext2_set_de_type (de, inode);
|
|
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);
|
|
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 inode *inode = page->mapping->host;
|
|
char *kaddr = page_address(page);
|
|
unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
|
|
unsigned to = ((char *)dir - kaddr) +
|
|
ext2_rec_len_from_disk(dir->rec_len);
|
|
loff_t pos;
|
|
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, __func__,
|
|
"zero-length directory entry");
|
|
err = -EIO;
|
|
goto out;
|
|
}
|
|
pde = de;
|
|
de = ext2_next_entry(de);
|
|
}
|
|
if (pde)
|
|
from = (char*)pde - (char*)page_address(page);
|
|
pos = page_offset(page) + from;
|
|
lock_page(page);
|
|
err = ext2_prepare_chunk(page, pos, to - from);
|
|
BUG_ON(err);
|
|
if (pde)
|
|
pde->rec_len = ext2_rec_len_to_disk(to - from);
|
|
dir->inode = 0;
|
|
err = ext2_commit_chunk(page, pos, to - from);
|
|
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 page *page = grab_cache_page(inode->i_mapping, 0);
|
|
unsigned chunk_size = ext2_chunk_size(inode);
|
|
struct ext2_dir_entry_2 * de;
|
|
int err;
|
|
void *kaddr;
|
|
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
err = ext2_prepare_chunk(page, 0, chunk_size);
|
|
if (err) {
|
|
unlock_page(page);
|
|
goto fail;
|
|
}
|
|
kaddr = kmap_atomic(page);
|
|
memset(kaddr, 0, chunk_size);
|
|
de = (struct ext2_dir_entry_2 *)kaddr;
|
|
de->name_len = 1;
|
|
de->rec_len = ext2_rec_len_to_disk(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 = ext2_rec_len_to_disk(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);
|
|
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);
|
|
int dir_has_error = 0;
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
char *kaddr;
|
|
ext2_dirent * de;
|
|
page = ext2_get_page(inode, i, dir_has_error);
|
|
|
|
if (IS_ERR(page)) {
|
|
dir_has_error = 1;
|
|
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, __func__,
|
|
"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;
|
|
}
|
|
|
|
const struct file_operations ext2_dir_operations = {
|
|
.llseek = generic_file_llseek,
|
|
.read = generic_read_dir,
|
|
.iterate = ext2_readdir,
|
|
.unlocked_ioctl = ext2_ioctl,
|
|
#ifdef CONFIG_COMPAT
|
|
.compat_ioctl = ext2_compat_ioctl,
|
|
#endif
|
|
.fsync = ext2_fsync,
|
|
};
|