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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
commit | 76cb841cb886eef6b3bee341a2266c76578724ad (patch) | |
tree | f5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /fs/minix/dir.c | |
parent | Initial commit. (diff) | |
download | linux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip |
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | fs/minix/dir.c | 469 |
1 files changed, 469 insertions, 0 deletions
diff --git a/fs/minix/dir.c b/fs/minix/dir.c new file mode 100644 index 000000000..dcfe5b253 --- /dev/null +++ b/fs/minix/dir.c @@ -0,0 +1,469 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/minix/dir.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * minix directory handling functions + * + * Updated to filesystem version 3 by Daniel Aragones + */ + +#include "minix.h" +#include <linux/buffer_head.h> +#include <linux/highmem.h> +#include <linux/swap.h> + +typedef struct minix_dir_entry minix_dirent; +typedef struct minix3_dir_entry minix3_dirent; + +static int minix_readdir(struct file *, struct dir_context *); + +const struct file_operations minix_dir_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate_shared = minix_readdir, + .fsync = generic_file_fsync, +}; + +static inline void dir_put_page(struct page *page) +{ + kunmap(page); + put_page(page); +} + +/* + * Return the offset into page `page_nr' of the last valid + * byte in that page, plus one. + */ +static unsigned +minix_last_byte(struct inode *inode, unsigned long page_nr) +{ + unsigned last_byte = PAGE_SIZE; + + if (page_nr == (inode->i_size >> PAGE_SHIFT)) + last_byte = inode->i_size & (PAGE_SIZE - 1); + return last_byte; +} + +static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len) +{ + struct address_space *mapping = page->mapping; + struct inode *dir = mapping->host; + int err = 0; + block_write_end(NULL, mapping, pos, len, len, page, NULL); + + if (pos+len > dir->i_size) { + i_size_write(dir, pos+len); + mark_inode_dirty(dir); + } + if (IS_DIRSYNC(dir)) + err = write_one_page(page); + else + unlock_page(page); + return err; +} + +static struct page * dir_get_page(struct inode *dir, unsigned long n) +{ + struct address_space *mapping = dir->i_mapping; + struct page *page = read_mapping_page(mapping, n, NULL); + if (!IS_ERR(page)) + kmap(page); + return page; +} + +static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi) +{ + return (void*)((char*)de + sbi->s_dirsize); +} + +static int minix_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + struct minix_sb_info *sbi = minix_sb(sb); + unsigned chunk_size = sbi->s_dirsize; + unsigned long npages = dir_pages(inode); + unsigned long pos = ctx->pos; + unsigned offset; + unsigned long n; + + ctx->pos = pos = ALIGN(pos, chunk_size); + if (pos >= inode->i_size) + return 0; + + offset = pos & ~PAGE_MASK; + n = pos >> PAGE_SHIFT; + + for ( ; n < npages; n++, offset = 0) { + char *p, *kaddr, *limit; + struct page *page = dir_get_page(inode, n); + + if (IS_ERR(page)) + continue; + kaddr = (char *)page_address(page); + p = kaddr+offset; + limit = kaddr + minix_last_byte(inode, n) - chunk_size; + for ( ; p <= limit; p = minix_next_entry(p, sbi)) { + const char *name; + __u32 inumber; + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)p; + name = de3->name; + inumber = de3->inode; + } else { + minix_dirent *de = (minix_dirent *)p; + name = de->name; + inumber = de->inode; + } + if (inumber) { + unsigned l = strnlen(name, sbi->s_namelen); + if (!dir_emit(ctx, name, l, + inumber, DT_UNKNOWN)) { + dir_put_page(page); + return 0; + } + } + ctx->pos += chunk_size; + } + dir_put_page(page); + } + return 0; +} + +static inline int namecompare(int len, int maxlen, + const char * name, const char * buffer) +{ + if (len < maxlen && buffer[len]) + return 0; + return !memcmp(name, buffer, len); +} + +/* + * minix_find_entry() + * + * finds an entry in the specified directory with the wanted name. It + * returns the cache buffer in which the entry was found, and the entry + * itself (as a parameter - res_dir). It does NOT read the inode of the + * entry - you'll have to do that yourself if you want to. + */ +minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page) +{ + const char * name = dentry->d_name.name; + int namelen = dentry->d_name.len; + struct inode * dir = d_inode(dentry->d_parent); + struct super_block * sb = dir->i_sb; + struct minix_sb_info * sbi = minix_sb(sb); + unsigned long n; + unsigned long npages = dir_pages(dir); + struct page *page = NULL; + char *p; + + char *namx; + __u32 inumber; + *res_page = NULL; + + for (n = 0; n < npages; n++) { + char *kaddr, *limit; + + page = dir_get_page(dir, n); + if (IS_ERR(page)) + continue; + + kaddr = (char*)page_address(page); + limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize; + for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)p; + namx = de3->name; + inumber = de3->inode; + } else { + minix_dirent *de = (minix_dirent *)p; + namx = de->name; + inumber = de->inode; + } + if (!inumber) + continue; + if (namecompare(namelen, sbi->s_namelen, name, namx)) + goto found; + } + dir_put_page(page); + } + return NULL; + +found: + *res_page = page; + return (minix_dirent *)p; +} + +int minix_add_link(struct dentry *dentry, struct inode *inode) +{ + struct inode *dir = d_inode(dentry->d_parent); + const char * name = dentry->d_name.name; + int namelen = dentry->d_name.len; + struct super_block * sb = dir->i_sb; + struct minix_sb_info * sbi = minix_sb(sb); + struct page *page = NULL; + unsigned long npages = dir_pages(dir); + unsigned long n; + char *kaddr, *p; + minix_dirent *de; + minix3_dirent *de3; + loff_t pos; + int err; + char *namx = NULL; + __u32 inumber; + + /* + * 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 *limit, *dir_end; + + page = dir_get_page(dir, n); + err = PTR_ERR(page); + if (IS_ERR(page)) + goto out; + lock_page(page); + kaddr = (char*)page_address(page); + dir_end = kaddr + minix_last_byte(dir, n); + limit = kaddr + PAGE_SIZE - sbi->s_dirsize; + for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { + de = (minix_dirent *)p; + de3 = (minix3_dirent *)p; + if (sbi->s_version == MINIX_V3) { + namx = de3->name; + inumber = de3->inode; + } else { + namx = de->name; + inumber = de->inode; + } + if (p == dir_end) { + /* We hit i_size */ + if (sbi->s_version == MINIX_V3) + de3->inode = 0; + else + de->inode = 0; + goto got_it; + } + if (!inumber) + goto got_it; + err = -EEXIST; + if (namecompare(namelen, sbi->s_namelen, name, namx)) + goto out_unlock; + } + unlock_page(page); + dir_put_page(page); + } + BUG(); + return -EINVAL; + +got_it: + pos = page_offset(page) + p - (char *)page_address(page); + err = minix_prepare_chunk(page, pos, sbi->s_dirsize); + if (err) + goto out_unlock; + memcpy (namx, name, namelen); + if (sbi->s_version == MINIX_V3) { + memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4); + de3->inode = inode->i_ino; + } else { + memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2); + de->inode = inode->i_ino; + } + err = dir_commit_chunk(page, pos, sbi->s_dirsize); + dir->i_mtime = dir->i_ctime = current_time(dir); + mark_inode_dirty(dir); +out_put: + dir_put_page(page); +out: + return err; +out_unlock: + unlock_page(page); + goto out_put; +} + +int minix_delete_entry(struct minix_dir_entry *de, struct page *page) +{ + struct inode *inode = page->mapping->host; + char *kaddr = page_address(page); + loff_t pos = page_offset(page) + (char*)de - kaddr; + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + unsigned len = sbi->s_dirsize; + int err; + + lock_page(page); + err = minix_prepare_chunk(page, pos, len); + if (err == 0) { + if (sbi->s_version == MINIX_V3) + ((minix3_dirent *) de)->inode = 0; + else + de->inode = 0; + err = dir_commit_chunk(page, pos, len); + } else { + unlock_page(page); + } + dir_put_page(page); + inode->i_ctime = inode->i_mtime = current_time(inode); + mark_inode_dirty(inode); + return err; +} + +int minix_make_empty(struct inode *inode, struct inode *dir) +{ + struct page *page = grab_cache_page(inode->i_mapping, 0); + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + char *kaddr; + int err; + + if (!page) + return -ENOMEM; + err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize); + if (err) { + unlock_page(page); + goto fail; + } + + kaddr = kmap_atomic(page); + memset(kaddr, 0, PAGE_SIZE); + + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)kaddr; + + de3->inode = inode->i_ino; + strcpy(de3->name, "."); + de3 = minix_next_entry(de3, sbi); + de3->inode = dir->i_ino; + strcpy(de3->name, ".."); + } else { + minix_dirent *de = (minix_dirent *)kaddr; + + de->inode = inode->i_ino; + strcpy(de->name, "."); + de = minix_next_entry(de, sbi); + de->inode = dir->i_ino; + strcpy(de->name, ".."); + } + kunmap_atomic(kaddr); + + err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize); +fail: + put_page(page); + return err; +} + +/* + * routine to check that the specified directory is empty (for rmdir) + */ +int minix_empty_dir(struct inode * inode) +{ + struct page *page = NULL; + unsigned long i, npages = dir_pages(inode); + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + char *name; + __u32 inumber; + + for (i = 0; i < npages; i++) { + char *p, *kaddr, *limit; + + page = dir_get_page(inode, i); + if (IS_ERR(page)) + continue; + + kaddr = (char *)page_address(page); + limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize; + for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)p; + name = de3->name; + inumber = de3->inode; + } else { + minix_dirent *de = (minix_dirent *)p; + name = de->name; + inumber = de->inode; + } + + if (inumber != 0) { + /* check for . and .. */ + if (name[0] != '.') + goto not_empty; + if (!name[1]) { + if (inumber != inode->i_ino) + goto not_empty; + } else if (name[1] != '.') + goto not_empty; + else if (name[2]) + goto not_empty; + } + } + dir_put_page(page); + } + return 1; + +not_empty: + dir_put_page(page); + return 0; +} + +/* Releases the page */ +void minix_set_link(struct minix_dir_entry *de, struct page *page, + struct inode *inode) +{ + struct inode *dir = page->mapping->host; + struct minix_sb_info *sbi = minix_sb(dir->i_sb); + loff_t pos = page_offset(page) + + (char *)de-(char*)page_address(page); + int err; + + lock_page(page); + + err = minix_prepare_chunk(page, pos, sbi->s_dirsize); + if (err == 0) { + if (sbi->s_version == MINIX_V3) + ((minix3_dirent *) de)->inode = inode->i_ino; + else + de->inode = inode->i_ino; + err = dir_commit_chunk(page, pos, sbi->s_dirsize); + } else { + unlock_page(page); + } + dir_put_page(page); + dir->i_mtime = dir->i_ctime = current_time(dir); + mark_inode_dirty(dir); +} + +struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p) +{ + struct page *page = dir_get_page(dir, 0); + struct minix_sb_info *sbi = minix_sb(dir->i_sb); + struct minix_dir_entry *de = NULL; + + if (!IS_ERR(page)) { + de = minix_next_entry(page_address(page), sbi); + *p = page; + } + return de; +} + +ino_t minix_inode_by_name(struct dentry *dentry) +{ + struct page *page; + struct minix_dir_entry *de = minix_find_entry(dentry, &page); + ino_t res = 0; + + if (de) { + struct address_space *mapping = page->mapping; + struct inode *inode = mapping->host; + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + + if (sbi->s_version == MINIX_V3) + res = ((minix3_dirent *) de)->inode; + else + res = de->inode; + dir_put_page(page); + } + return res; +} |