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![Matthew Wilcox (Oracle)](/assets/img/avatar_default.png)
If read_mapping_page() encounters an error, it returns an errno, not a page with PageError set, so this test is not needed. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
679 lines
16 KiB
C
679 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* NILFS directory entry operations
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*
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* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
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*
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* Modified for NILFS by Amagai Yoshiji.
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*/
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/*
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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 <linux/pagemap.h>
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#include "nilfs.h"
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#include "page.h"
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static inline unsigned int nilfs_rec_len_from_disk(__le16 dlen)
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{
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unsigned int len = le16_to_cpu(dlen);
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#if (PAGE_SIZE >= 65536)
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if (len == NILFS_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 nilfs_rec_len_to_disk(unsigned int len)
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{
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#if (PAGE_SIZE >= 65536)
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if (len == (1 << 16))
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return cpu_to_le16(NILFS_MAX_REC_LEN);
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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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* nilfs 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 int nilfs_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 nilfs_put_page(struct page *page)
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{
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kunmap(page);
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put_page(page);
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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 int nilfs_last_byte(struct inode *inode, unsigned long page_nr)
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{
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unsigned int last_byte = inode->i_size;
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last_byte -= page_nr << PAGE_SHIFT;
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if (last_byte > PAGE_SIZE)
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last_byte = PAGE_SIZE;
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return last_byte;
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}
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static int nilfs_prepare_chunk(struct page *page, unsigned int from,
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unsigned int to)
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{
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loff_t pos = page_offset(page) + from;
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return __block_write_begin(page, pos, to - from, nilfs_get_block);
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}
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static void nilfs_commit_chunk(struct page *page,
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struct address_space *mapping,
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unsigned int from, unsigned int to)
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{
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struct inode *dir = mapping->host;
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loff_t pos = page_offset(page) + from;
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unsigned int len = to - from;
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unsigned int nr_dirty, copied;
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int err;
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nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
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copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
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if (pos + copied > dir->i_size)
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i_size_write(dir, pos + copied);
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if (IS_DIRSYNC(dir))
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nilfs_set_transaction_flag(NILFS_TI_SYNC);
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err = nilfs_set_file_dirty(dir, nr_dirty);
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WARN_ON(err); /* do not happen */
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unlock_page(page);
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}
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static bool nilfs_check_page(struct page *page)
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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 int chunk_size = nilfs_chunk_size(dir);
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char *kaddr = page_address(page);
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unsigned int offs, rec_len;
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unsigned int limit = PAGE_SIZE;
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struct nilfs_dir_entry *p;
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char *error;
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if ((dir->i_size >> PAGE_SHIFT) == page->index) {
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limit = dir->i_size & ~PAGE_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 - NILFS_DIR_REC_LEN(1); offs += rec_len) {
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p = (struct nilfs_dir_entry *)(kaddr + offs);
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rec_len = nilfs_rec_len_from_disk(p->rec_len);
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if (rec_len < NILFS_DIR_REC_LEN(1))
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goto Eshort;
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if (rec_len & 3)
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goto Ealign;
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if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
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goto Enamelen;
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if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
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goto Espan;
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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 true;
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/* Too bad, we had an error */
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Ebadsize:
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nilfs_error(sb,
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"size of directory #%lu is not a multiple of chunk size",
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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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bad_entry:
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nilfs_error(sb,
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"bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
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dir->i_ino, error, (page->index << PAGE_SHIFT) + offs,
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(unsigned long)le64_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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p = (struct nilfs_dir_entry *)(kaddr + offs);
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nilfs_error(sb,
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"entry in directory #%lu spans the page boundary offset=%lu, inode=%lu",
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dir->i_ino, (page->index << PAGE_SHIFT) + offs,
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(unsigned long)le64_to_cpu(p->inode));
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fail:
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SetPageError(page);
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return false;
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}
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static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
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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 (unlikely(!PageChecked(page))) {
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if (!nilfs_check_page(page))
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goto fail;
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}
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}
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return page;
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fail:
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nilfs_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, nilfs_match returns 1 for success, 0 for failure.
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*
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* len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
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*/
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static int
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nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *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 struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
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{
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return (struct nilfs_dir_entry *)((char *)p +
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nilfs_rec_len_from_disk(p->rec_len));
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}
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static unsigned char
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nilfs_filetype_table[NILFS_FT_MAX] = {
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[NILFS_FT_UNKNOWN] = DT_UNKNOWN,
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[NILFS_FT_REG_FILE] = DT_REG,
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[NILFS_FT_DIR] = DT_DIR,
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[NILFS_FT_CHRDEV] = DT_CHR,
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[NILFS_FT_BLKDEV] = DT_BLK,
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[NILFS_FT_FIFO] = DT_FIFO,
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[NILFS_FT_SOCK] = DT_SOCK,
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[NILFS_FT_SYMLINK] = DT_LNK,
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};
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#define S_SHIFT 12
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static unsigned char
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nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
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[S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
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[S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
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[S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
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[S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
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[S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
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[S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
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[S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
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};
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static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
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{
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umode_t mode = inode->i_mode;
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de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
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}
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static int nilfs_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_MASK;
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unsigned long n = pos >> PAGE_SHIFT;
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unsigned long npages = dir_pages(inode);
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if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
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return 0;
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for ( ; n < npages; n++, offset = 0) {
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char *kaddr, *limit;
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struct nilfs_dir_entry *de;
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struct page *page = nilfs_get_page(inode, n);
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if (IS_ERR(page)) {
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nilfs_error(sb, "bad page in #%lu", inode->i_ino);
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ctx->pos += PAGE_SIZE - offset;
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return -EIO;
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}
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kaddr = page_address(page);
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de = (struct nilfs_dir_entry *)(kaddr + offset);
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limit = kaddr + nilfs_last_byte(inode, n) -
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NILFS_DIR_REC_LEN(1);
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for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
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if (de->rec_len == 0) {
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nilfs_error(sb, "zero-length directory entry");
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nilfs_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 t;
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if (de->file_type < NILFS_FT_MAX)
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t = nilfs_filetype_table[de->file_type];
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else
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t = DT_UNKNOWN;
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if (!dir_emit(ctx, de->name, de->name_len,
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le64_to_cpu(de->inode), t)) {
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nilfs_put_page(page);
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return 0;
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}
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}
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ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
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}
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nilfs_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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* nilfs_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, and the entry itself
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* (as a parameter - res_dir). 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 nilfs_dir_entry *
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nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
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struct page **res_page)
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{
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const unsigned char *name = qstr->name;
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int namelen = qstr->len;
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unsigned int reclen = NILFS_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 nilfs_inode_info *ei = NILFS_I(dir);
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struct nilfs_dir_entry *de;
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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 = nilfs_get_page(dir, n);
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if (!IS_ERR(page)) {
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kaddr = page_address(page);
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de = (struct nilfs_dir_entry *)kaddr;
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kaddr += nilfs_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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nilfs_error(dir->i_sb,
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"zero-length directory entry");
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nilfs_put_page(page);
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goto out;
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}
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if (nilfs_match(namelen, name, de))
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goto found;
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de = nilfs_next_entry(de);
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}
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nilfs_put_page(page);
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}
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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_SHIFT - 9)))) {
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nilfs_error(dir->i_sb,
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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 nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
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{
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struct page *page = nilfs_get_page(dir, 0);
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struct nilfs_dir_entry *de = NULL;
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if (!IS_ERR(page)) {
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de = nilfs_next_entry(
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(struct nilfs_dir_entry *)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 nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
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{
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ino_t res = 0;
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struct nilfs_dir_entry *de;
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struct page *page;
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de = nilfs_find_entry(dir, qstr, &page);
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if (de) {
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res = le64_to_cpu(de->inode);
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kunmap(page);
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put_page(page);
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}
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return res;
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}
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/* Releases the page */
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void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
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struct page *page, struct inode *inode)
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{
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unsigned int from = (char *)de - (char *)page_address(page);
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unsigned int to = from + nilfs_rec_len_from_disk(de->rec_len);
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struct address_space *mapping = page->mapping;
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int err;
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lock_page(page);
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err = nilfs_prepare_chunk(page, from, to);
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BUG_ON(err);
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de->inode = cpu_to_le64(inode->i_ino);
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nilfs_set_de_type(de, inode);
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nilfs_commit_chunk(page, mapping, from, to);
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nilfs_put_page(page);
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dir->i_mtime = dir->i_ctime = current_time(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 nilfs_add_link(struct dentry *dentry, struct inode *inode)
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{
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struct inode *dir = d_inode(dentry->d_parent);
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const unsigned char *name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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unsigned int chunk_size = nilfs_chunk_size(dir);
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unsigned int reclen = NILFS_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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struct nilfs_dir_entry *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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unsigned int from, to;
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int err;
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/*
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* We take care of directory expansion in the same loop.
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* This code plays outside i_size, so it locks the page
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* to protect that region.
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*/
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for (n = 0; n <= npages; n++) {
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char *dir_end;
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page = nilfs_get_page(dir, n);
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err = PTR_ERR(page);
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if (IS_ERR(page))
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goto out;
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lock_page(page);
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kaddr = page_address(page);
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dir_end = kaddr + nilfs_last_byte(dir, n);
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de = (struct nilfs_dir_entry *)kaddr;
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kaddr += PAGE_SIZE - reclen;
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while ((char *)de <= kaddr) {
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if ((char *)de == dir_end) {
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/* We hit i_size */
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name_len = 0;
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rec_len = chunk_size;
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de->rec_len = nilfs_rec_len_to_disk(chunk_size);
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de->inode = 0;
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goto got_it;
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}
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if (de->rec_len == 0) {
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nilfs_error(dir->i_sb,
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"zero-length directory entry");
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err = -EIO;
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goto out_unlock;
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}
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err = -EEXIST;
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if (nilfs_match(namelen, name, de))
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goto out_unlock;
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name_len = NILFS_DIR_REC_LEN(de->name_len);
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rec_len = nilfs_rec_len_from_disk(de->rec_len);
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if (!de->inode && rec_len >= reclen)
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goto got_it;
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if (rec_len >= name_len + reclen)
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goto got_it;
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de = (struct nilfs_dir_entry *)((char *)de + rec_len);
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}
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unlock_page(page);
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nilfs_put_page(page);
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}
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BUG();
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return -EINVAL;
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|
|
got_it:
|
|
from = (char *)de - (char *)page_address(page);
|
|
to = from + rec_len;
|
|
err = nilfs_prepare_chunk(page, from, to);
|
|
if (err)
|
|
goto out_unlock;
|
|
if (de->inode) {
|
|
struct nilfs_dir_entry *de1;
|
|
|
|
de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
|
|
de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
|
|
de->rec_len = nilfs_rec_len_to_disk(name_len);
|
|
de = de1;
|
|
}
|
|
de->name_len = namelen;
|
|
memcpy(de->name, name, namelen);
|
|
de->inode = cpu_to_le64(inode->i_ino);
|
|
nilfs_set_de_type(de, inode);
|
|
nilfs_commit_chunk(page, page->mapping, from, to);
|
|
dir->i_mtime = dir->i_ctime = current_time(dir);
|
|
nilfs_mark_inode_dirty(dir);
|
|
/* OFFSET_CACHE */
|
|
out_put:
|
|
nilfs_put_page(page);
|
|
out:
|
|
return err;
|
|
out_unlock:
|
|
unlock_page(page);
|
|
goto out_put;
|
|
}
|
|
|
|
/*
|
|
* nilfs_delete_entry deletes a directory entry by merging it with the
|
|
* previous entry. Page is up-to-date. Releases the page.
|
|
*/
|
|
int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
|
|
{
|
|
struct address_space *mapping = page->mapping;
|
|
struct inode *inode = mapping->host;
|
|
char *kaddr = page_address(page);
|
|
unsigned int from, to;
|
|
struct nilfs_dir_entry *de, *pde = NULL;
|
|
int err;
|
|
|
|
from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
|
|
to = ((char *)dir - kaddr) + nilfs_rec_len_from_disk(dir->rec_len);
|
|
de = (struct nilfs_dir_entry *)(kaddr + from);
|
|
|
|
while ((char *)de < (char *)dir) {
|
|
if (de->rec_len == 0) {
|
|
nilfs_error(inode->i_sb,
|
|
"zero-length directory entry");
|
|
err = -EIO;
|
|
goto out;
|
|
}
|
|
pde = de;
|
|
de = nilfs_next_entry(de);
|
|
}
|
|
if (pde)
|
|
from = (char *)pde - (char *)page_address(page);
|
|
lock_page(page);
|
|
err = nilfs_prepare_chunk(page, from, to);
|
|
BUG_ON(err);
|
|
if (pde)
|
|
pde->rec_len = nilfs_rec_len_to_disk(to - from);
|
|
dir->inode = 0;
|
|
nilfs_commit_chunk(page, mapping, from, to);
|
|
inode->i_ctime = inode->i_mtime = current_time(inode);
|
|
out:
|
|
nilfs_put_page(page);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Set the first fragment of directory.
|
|
*/
|
|
int nilfs_make_empty(struct inode *inode, struct inode *parent)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct page *page = grab_cache_page(mapping, 0);
|
|
unsigned int chunk_size = nilfs_chunk_size(inode);
|
|
struct nilfs_dir_entry *de;
|
|
int err;
|
|
void *kaddr;
|
|
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
err = nilfs_prepare_chunk(page, 0, chunk_size);
|
|
if (unlikely(err)) {
|
|
unlock_page(page);
|
|
goto fail;
|
|
}
|
|
kaddr = kmap_atomic(page);
|
|
memset(kaddr, 0, chunk_size);
|
|
de = (struct nilfs_dir_entry *)kaddr;
|
|
de->name_len = 1;
|
|
de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
|
|
memcpy(de->name, ".\0\0", 4);
|
|
de->inode = cpu_to_le64(inode->i_ino);
|
|
nilfs_set_de_type(de, inode);
|
|
|
|
de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
|
|
de->name_len = 2;
|
|
de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
|
|
de->inode = cpu_to_le64(parent->i_ino);
|
|
memcpy(de->name, "..\0", 4);
|
|
nilfs_set_de_type(de, inode);
|
|
kunmap_atomic(kaddr);
|
|
nilfs_commit_chunk(page, mapping, 0, chunk_size);
|
|
fail:
|
|
put_page(page);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* routine to check that the specified directory is empty (for rmdir)
|
|
*/
|
|
int nilfs_empty_dir(struct inode *inode)
|
|
{
|
|
struct page *page = NULL;
|
|
unsigned long i, npages = dir_pages(inode);
|
|
|
|
for (i = 0; i < npages; i++) {
|
|
char *kaddr;
|
|
struct nilfs_dir_entry *de;
|
|
|
|
page = nilfs_get_page(inode, i);
|
|
if (IS_ERR(page))
|
|
continue;
|
|
|
|
kaddr = page_address(page);
|
|
de = (struct nilfs_dir_entry *)kaddr;
|
|
kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
|
|
|
|
while ((char *)de <= kaddr) {
|
|
if (de->rec_len == 0) {
|
|
nilfs_error(inode->i_sb,
|
|
"zero-length directory entry (kaddr=%p, de=%p)",
|
|
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_le64(inode->i_ino))
|
|
goto not_empty;
|
|
} else if (de->name[1] != '.')
|
|
goto not_empty;
|
|
}
|
|
de = nilfs_next_entry(de);
|
|
}
|
|
nilfs_put_page(page);
|
|
}
|
|
return 1;
|
|
|
|
not_empty:
|
|
nilfs_put_page(page);
|
|
return 0;
|
|
}
|
|
|
|
const struct file_operations nilfs_dir_operations = {
|
|
.llseek = generic_file_llseek,
|
|
.read = generic_read_dir,
|
|
.iterate_shared = nilfs_readdir,
|
|
.unlocked_ioctl = nilfs_ioctl,
|
|
#ifdef CONFIG_COMPAT
|
|
.compat_ioctl = nilfs_compat_ioctl,
|
|
#endif /* CONFIG_COMPAT */
|
|
.fsync = nilfs_sync_file,
|
|
|
|
};
|