Linux 4.18.10

[linux/fpc-iii.git] / fs / exofs / dir.c

/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger (avishay@gmail.com)
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <ooo@electrozaur.com>
 *
 * Copyrights for code taken from ext2:
 *     Copyright (C) 1992, 1993, 1994, 1995
 *     Remy Card (card@masi.ibp.fr)
 *     Laboratoire MASI - Institut Blaise Pascal
 *     Universite Pierre et Marie Curie (Paris VI)
 *     from
 *     linux/fs/minix/inode.c
 *     Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is part of exofs.
 *
 * exofs is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.  Since it is based on ext2, and the only
 * valid version of GPL for the Linux kernel is version 2, the only valid
 * version of GPL for exofs is version 2.
 *
 * exofs is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with exofs; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/iversion.h>
#include "exofs.h"

static inline unsigned exofs_chunk_size(struct inode *inode)
{
        return inode->i_sb->s_blocksize;
}

static inline void exofs_put_page(struct page *page)
{
        kunmap(page);
        put_page(page);
}

static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
{
        loff_t last_byte = inode->i_size;

        last_byte -= page_nr << PAGE_SHIFT;
        if (last_byte > PAGE_SIZE)
                last_byte = PAGE_SIZE;
        return last_byte;
}

static int exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
        struct address_space *mapping = page->mapping;
        struct inode *dir = mapping->host;
        int err = 0;

        inode_inc_iversion(dir);

        if (!PageUptodate(page))
                SetPageUptodate(page);

        if (pos+len > dir->i_size) {
                i_size_write(dir, pos+len);
                mark_inode_dirty(dir);
        }
        set_page_dirty(page);

        if (IS_DIRSYNC(dir))
                err = write_one_page(page);
        else
                unlock_page(page);

        return err;
}

static bool exofs_check_page(struct page *page)
{
        struct inode *dir = page->mapping->host;
        unsigned chunk_size = exofs_chunk_size(dir);
        char *kaddr = page_address(page);
        unsigned offs, rec_len;
        unsigned limit = PAGE_SIZE;
        struct exofs_dir_entry *p;
        char *error;

        /* if the page is the last one in the directory */
        if ((dir->i_size >> PAGE_SHIFT) == page->index) {
                limit = dir->i_size & ~PAGE_MASK;
                if (limit & (chunk_size - 1))
                        goto Ebadsize;
                if (!limit)
                        goto out;
        }
        for (offs = 0; offs <= limit - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
                p = (struct exofs_dir_entry *)(kaddr + offs);
                rec_len = le16_to_cpu(p->rec_len);

                if (rec_len < EXOFS_DIR_REC_LEN(1))
                        goto Eshort;
                if (rec_len & 3)
                        goto Ealign;
                if (rec_len < EXOFS_DIR_REC_LEN(p->name_len))
                        goto Enamelen;
                if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
                        goto Espan;
        }
        if (offs != limit)
                goto Eend;
out:
        SetPageChecked(page);
        return true;

Ebadsize:
        EXOFS_ERR("ERROR [exofs_check_page]: "
                "size of directory(0x%lx) is not a multiple of chunk size\n",
                dir->i_ino
        );
        goto fail;
Eshort:
        error = "rec_len is smaller than minimal";
        goto bad_entry;
Ealign:
        error = "unaligned directory entry";
        goto bad_entry;
Enamelen:
        error = "rec_len is too small for name_len";
        goto bad_entry;
Espan:
        error = "directory entry across blocks";
        goto bad_entry;
bad_entry:
        EXOFS_ERR(
                "ERROR [exofs_check_page]: bad entry in directory(0x%lx): %s - "
                "offset=%lu, inode=0x%llx, rec_len=%d, name_len=%d\n",
                dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
                _LLU(le64_to_cpu(p->inode_no)),
                rec_len, p->name_len);
        goto fail;
Eend:
        p = (struct exofs_dir_entry *)(kaddr + offs);
        EXOFS_ERR("ERROR [exofs_check_page]: "
                "entry in directory(0x%lx) spans the page boundary"
                "offset=%lu, inode=0x%llx\n",
                dir->i_ino, (page->index<<PAGE_SHIFT)+offs,
                _LLU(le64_to_cpu(p->inode_no)));
fail:
        SetPageError(page);
        return false;
}

static struct page *exofs_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);
                if (unlikely(!PageChecked(page))) {
                        if (PageError(page) || !exofs_check_page(page))
                                goto fail;
                }
        }
        return page;

fail:
        exofs_put_page(page);
        return ERR_PTR(-EIO);
}

static inline int exofs_match(int len, const unsigned char *name,
                                        struct exofs_dir_entry *de)
{
        if (len != de->name_len)
                return 0;
        if (!de->inode_no)
                return 0;
        return !memcmp(name, de->name, len);
}

static inline
struct exofs_dir_entry *exofs_next_entry(struct exofs_dir_entry *p)
{
        return (struct exofs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
}

static inline unsigned
exofs_validate_entry(char *base, unsigned offset, unsigned mask)
{
        struct exofs_dir_entry *de = (struct exofs_dir_entry *)(base + offset);
        struct exofs_dir_entry *p =
                        (struct exofs_dir_entry *)(base + (offset&mask));
        while ((char *)p < (char *)de) {
                if (p->rec_len == 0)
                        break;
                p = exofs_next_entry(p);
        }
        return (char *)p - base;
}

static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
        [EXOFS_FT_UNKNOWN]      = DT_UNKNOWN,
        [EXOFS_FT_REG_FILE]     = DT_REG,
        [EXOFS_FT_DIR]          = DT_DIR,
        [EXOFS_FT_CHRDEV]       = DT_CHR,
        [EXOFS_FT_BLKDEV]       = DT_BLK,
        [EXOFS_FT_FIFO]         = DT_FIFO,
        [EXOFS_FT_SOCK]         = DT_SOCK,
        [EXOFS_FT_SYMLINK]      = DT_LNK,
};

#define S_SHIFT 12
static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
        [S_IFREG >> S_SHIFT]    = EXOFS_FT_REG_FILE,
        [S_IFDIR >> S_SHIFT]    = EXOFS_FT_DIR,
        [S_IFCHR >> S_SHIFT]    = EXOFS_FT_CHRDEV,
        [S_IFBLK >> S_SHIFT]    = EXOFS_FT_BLKDEV,
        [S_IFIFO >> S_SHIFT]    = EXOFS_FT_FIFO,
        [S_IFSOCK >> S_SHIFT]   = EXOFS_FT_SOCK,
        [S_IFLNK >> S_SHIFT]    = EXOFS_FT_SYMLINK,
};

static inline
void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
{
        umode_t mode = inode->i_mode;
        de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
}

static int
exofs_readdir(struct file *file, struct dir_context *ctx)
{
        loff_t pos = ctx->pos;
        struct inode *inode = file_inode(file);
        unsigned int offset = pos & ~PAGE_MASK;
        unsigned long n = pos >> PAGE_SHIFT;
        unsigned long npages = dir_pages(inode);
        unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
        bool need_revalidate = !inode_eq_iversion(inode, file->f_version);

        if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
                return 0;

        for ( ; n < npages; n++, offset = 0) {
                char *kaddr, *limit;
                struct exofs_dir_entry *de;
                struct page *page = exofs_get_page(inode, n);

                if (IS_ERR(page)) {
                        EXOFS_ERR("ERROR: bad page in directory(0x%lx)\n",
                                  inode->i_ino);
                        ctx->pos += PAGE_SIZE - offset;
                        return PTR_ERR(page);
                }
                kaddr = page_address(page);
                if (unlikely(need_revalidate)) {
                        if (offset) {
                                offset = exofs_validate_entry(kaddr, offset,
                                                                chunk_mask);
                                ctx->pos = (n<<PAGE_SHIFT) + offset;
                        }
                        file->f_version = inode_query_iversion(inode);
                        need_revalidate = false;
                }
                de = (struct exofs_dir_entry *)(kaddr + offset);
                limit = kaddr + exofs_last_byte(inode, n) -
                                                        EXOFS_DIR_REC_LEN(1);
                for (; (char *)de <= limit; de = exofs_next_entry(de)) {
                        if (de->rec_len == 0) {
                                EXOFS_ERR("ERROR: "
                                     "zero-length entry in directory(0x%lx)\n",
                                     inode->i_ino);
                                exofs_put_page(page);
                                return -EIO;
                        }
                        if (de->inode_no) {
                                unsigned char t;

                                if (de->file_type < EXOFS_FT_MAX)
                                        t = exofs_filetype_table[de->file_type];
                                else
                                        t = DT_UNKNOWN;

                                if (!dir_emit(ctx, de->name, de->name_len,
                                                le64_to_cpu(de->inode_no),
                                                t)) {
                                        exofs_put_page(page);
                                        return 0;
                                }
                        }
                        ctx->pos += le16_to_cpu(de->rec_len);
                }
                exofs_put_page(page);
        }
        return 0;
}

struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
                        struct dentry *dentry, struct page **res_page)
{
        const unsigned char *name = dentry->d_name.name;
        int namelen = dentry->d_name.len;
        unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
        unsigned long start, n;
        unsigned long npages = dir_pages(dir);
        struct page *page = NULL;
        struct exofs_i_info *oi = exofs_i(dir);
        struct exofs_dir_entry *de;

        if (npages == 0)
                goto out;

        *res_page = NULL;

        start = oi->i_dir_start_lookup;
        if (start >= npages)
                start = 0;
        n = start;
        do {
                char *kaddr;
                page = exofs_get_page(dir, n);
                if (!IS_ERR(page)) {
                        kaddr = page_address(page);
                        de = (struct exofs_dir_entry *) kaddr;
                        kaddr += exofs_last_byte(dir, n) - reclen;
                        while ((char *) de <= kaddr) {
                                if (de->rec_len == 0) {
                                        EXOFS_ERR("ERROR: zero-length entry in "
                                                  "directory(0x%lx)\n",
                                                  dir->i_ino);
                                        exofs_put_page(page);
                                        goto out;
                                }
                                if (exofs_match(namelen, name, de))
                                        goto found;
                                de = exofs_next_entry(de);
                        }
                        exofs_put_page(page);
                }
                if (++n >= npages)
                        n = 0;
        } while (n != start);
out:
        return NULL;

found:
        *res_page = page;
        oi->i_dir_start_lookup = n;
        return de;
}

struct exofs_dir_entry *exofs_dotdot(struct inode *dir, struct page **p)
{
        struct page *page = exofs_get_page(dir, 0);
        struct exofs_dir_entry *de = NULL;

        if (!IS_ERR(page)) {
                de = exofs_next_entry(
                                (struct exofs_dir_entry *)page_address(page));
                *p = page;
        }
        return de;
}

ino_t exofs_parent_ino(struct dentry *child)
{
        struct page *page;
        struct exofs_dir_entry *de;
        ino_t ino;

        de = exofs_dotdot(d_inode(child), &page);
        if (!de)
                return 0;

        ino = le64_to_cpu(de->inode_no);
        exofs_put_page(page);
        return ino;
}

ino_t exofs_inode_by_name(struct inode *dir, struct dentry *dentry)
{
        ino_t res = 0;
        struct exofs_dir_entry *de;
        struct page *page;

        de = exofs_find_entry(dir, dentry, &page);
        if (de) {
                res = le64_to_cpu(de->inode_no);
                exofs_put_page(page);
        }
        return res;
}

int exofs_set_link(struct inode *dir, struct exofs_dir_entry *de,
                        struct page *page, struct inode *inode)
{
        loff_t pos = page_offset(page) +
                        (char *) de - (char *) page_address(page);
        unsigned len = le16_to_cpu(de->rec_len);
        int err;

        lock_page(page);
        err = exofs_write_begin(NULL, page->mapping, pos, len, 0, &page, NULL);
        if (err)
                EXOFS_ERR("exofs_set_link: exofs_write_begin FAILED => %d\n",
                          err);

        de->inode_no = cpu_to_le64(inode->i_ino);
        exofs_set_de_type(de, inode);
        if (likely(!err))
                err = exofs_commit_chunk(page, pos, len);
        exofs_put_page(page);
        dir->i_mtime = dir->i_ctime = current_time(dir);
        mark_inode_dirty(dir);
        return err;
}

int exofs_add_link(struct dentry *dentry, struct inode *inode)
{
        struct inode *dir = d_inode(dentry->d_parent);
        const unsigned char *name = dentry->d_name.name;
        int namelen = dentry->d_name.len;
        unsigned chunk_size = exofs_chunk_size(dir);
        unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
        unsigned short rec_len, name_len;
        struct page *page = NULL;
        struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
        struct exofs_dir_entry *de;
        unsigned long npages = dir_pages(dir);
        unsigned long n;
        char *kaddr;
        loff_t pos;
        int err;

        for (n = 0; n <= npages; n++) {
                char *dir_end;

                page = exofs_get_page(dir, n);
                err = PTR_ERR(page);
                if (IS_ERR(page))
                        goto out;
                lock_page(page);
                kaddr = page_address(page);
                dir_end = kaddr + exofs_last_byte(dir, n);
                de = (struct exofs_dir_entry *)kaddr;
                kaddr += PAGE_SIZE - reclen;
                while ((char *)de <= kaddr) {
                        if ((char *)de == dir_end) {
                                name_len = 0;
                                rec_len = chunk_size;
                                de->rec_len = cpu_to_le16(chunk_size);
                                de->inode_no = 0;
                                goto got_it;
                        }
                        if (de->rec_len == 0) {
                                EXOFS_ERR("ERROR: exofs_add_link: "
                                      "zero-length entry in directory(0x%lx)\n",
                                      inode->i_ino);
                                err = -EIO;
                                goto out_unlock;
                        }
                        err = -EEXIST;
                        if (exofs_match(namelen, name, de))
                                goto out_unlock;
                        name_len = EXOFS_DIR_REC_LEN(de->name_len);
                        rec_len = le16_to_cpu(de->rec_len);
                        if (!de->inode_no && rec_len >= reclen)
                                goto got_it;
                        if (rec_len >= name_len + reclen)
                                goto got_it;
                        de = (struct exofs_dir_entry *) ((char *) de + rec_len);
                }
                unlock_page(page);
                exofs_put_page(page);
        }

        EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=0x%lx\n",
                  dentry, inode->i_ino);
        return -EINVAL;

got_it:
        pos = page_offset(page) +
                (char *)de - (char *)page_address(page);
        err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
                                                        &page, NULL);
        if (err)
                goto out_unlock;
        if (de->inode_no) {
                struct exofs_dir_entry *de1 =
                        (struct exofs_dir_entry *)((char *)de + name_len);
                de1->rec_len = cpu_to_le16(rec_len - name_len);
                de->rec_len = cpu_to_le16(name_len);
                de = de1;
        }
        de->name_len = namelen;
        memcpy(de->name, name, namelen);
        de->inode_no = cpu_to_le64(inode->i_ino);
        exofs_set_de_type(de, inode);
        err = exofs_commit_chunk(page, pos, rec_len);
        dir->i_mtime = dir->i_ctime = current_time(dir);
        mark_inode_dirty(dir);
        sbi->s_numfiles++;

out_put:
        exofs_put_page(page);
out:
        return err;
out_unlock:
        unlock_page(page);
        goto out_put;
}

int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
{
        struct address_space *mapping = page->mapping;
        struct inode *inode = mapping->host;
        struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
        char *kaddr = page_address(page);
        unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
        unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
        loff_t pos;
        struct exofs_dir_entry *pde = NULL;
        struct exofs_dir_entry *de = (struct exofs_dir_entry *) (kaddr + from);
        int err;

        while (de < dir) {
                if (de->rec_len == 0) {
                        EXOFS_ERR("ERROR: exofs_delete_entry:"
                                  "zero-length entry in directory(0x%lx)\n",
                                  inode->i_ino);
                        err = -EIO;
                        goto out;
                }
                pde = de;
                de = exofs_next_entry(de);
        }
        if (pde)
                from = (char *)pde - (char *)page_address(page);
        pos = page_offset(page) + from;
        lock_page(page);
        err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
                                                        &page, NULL);
        if (err)
                EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILED => %d\n",
                          err);
        if (pde)
                pde->rec_len = cpu_to_le16(to - from);
        dir->inode_no = 0;
        if (likely(!err))
                err = exofs_commit_chunk(page, pos, to - from);
        inode->i_ctime = inode->i_mtime = current_time(inode);
        mark_inode_dirty(inode);
        sbi->s_numfiles--;
out:
        exofs_put_page(page);
        return err;
}

/* kept aligned on 4 bytes */
#define THIS_DIR ".\0\0"
#define PARENT_DIR "..\0"

int exofs_make_empty(struct inode *inode, struct inode *parent)
{
        struct address_space *mapping = inode->i_mapping;
        struct page *page = grab_cache_page(mapping, 0);
        unsigned chunk_size = exofs_chunk_size(inode);
        struct exofs_dir_entry *de;
        int err;
        void *kaddr;

        if (!page)
                return -ENOMEM;

        err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
                                                        &page, NULL);
        if (err) {
                unlock_page(page);
                goto fail;
        }

        kaddr = kmap_atomic(page);
        de = (struct exofs_dir_entry *)kaddr;
        de->name_len = 1;
        de->rec_len = cpu_to_le16(EXOFS_DIR_REC_LEN(1));
        memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
        de->inode_no = cpu_to_le64(inode->i_ino);
        exofs_set_de_type(de, inode);

        de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
        de->name_len = 2;
        de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
        de->inode_no = cpu_to_le64(parent->i_ino);
        memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
        exofs_set_de_type(de, inode);
        kunmap_atomic(kaddr);
        err = exofs_commit_chunk(page, 0, chunk_size);
fail:
        put_page(page);
        return err;
}

int exofs_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 exofs_dir_entry *de;
                page = exofs_get_page(inode, i);

                if (IS_ERR(page))
                        continue;

                kaddr = page_address(page);
                de = (struct exofs_dir_entry *)kaddr;
                kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);

                while ((char *)de <= kaddr) {
                        if (de->rec_len == 0) {
                                EXOFS_ERR("ERROR: exofs_empty_dir: "
                                          "zero-length directory entry"
                                          "kaddr=%p, de=%p\n", kaddr, de);
                                goto not_empty;
                        }
                        if (de->inode_no != 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 (le64_to_cpu(de->inode_no) !=
                                            inode->i_ino)
                                                goto not_empty;
                                } else if (de->name[1] != '.')
                                        goto not_empty;
                        }
                        de = exofs_next_entry(de);
                }
                exofs_put_page(page);
        }
        return 1;

not_empty:
        exofs_put_page(page);
        return 0;
}

const struct file_operations exofs_dir_operations = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .iterate_shared = exofs_readdir,
};