file.c

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/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 * Copyright © 2004-2010 David Woodhouse <[email protected]>
 *
 * Created by David Woodhouse <[email protected]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/crc32.h>
#include <linux/jffs2.h>
#include "nodelist.h"

static int jffs2_write_end(struct file *filp, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned copied,
            struct page *pg, void *fsdata);
static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata);
static int jffs2_readpage (struct file *filp, struct page *pg);

int jffs2_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
    struct inode *inode = filp->f_mapping->host;
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    int ret;

    ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
    if (ret)
        return ret;

    mutex_lock(&inode->i_mutex);
    /* Trigger GC to flush any pending writes for this inode */
    jffs2_flush_wbuf_gc(c, inode->i_ino);
    mutex_unlock(&inode->i_mutex);

    return 0;
}

const struct file_operations jffs2_file_operations =
{
    .llseek =   generic_file_llseek,
    .open =     generic_file_open,
    .read =     do_sync_read,
    .aio_read = generic_file_aio_read,
    .write =    do_sync_write,
    .aio_write =    generic_file_aio_write,
    .unlocked_ioctl=jffs2_ioctl,
    .mmap =     generic_file_readonly_mmap,
    .fsync =    jffs2_fsync,
    .splice_read =  generic_file_splice_read,
};

/* jffs2_file_inode_operations */

const struct inode_operations jffs2_file_inode_operations =
{
    .get_acl =  jffs2_get_acl,
    .setattr =  jffs2_setattr,
    .setxattr = jffs2_setxattr,
    .getxattr = jffs2_getxattr,
    .listxattr =    jffs2_listxattr,
    .removexattr =  jffs2_removexattr
};

const struct address_space_operations jffs2_file_address_operations =
{
    .readpage = jffs2_readpage,
    .write_begin =  jffs2_write_begin,
    .write_end =    jffs2_write_end,
};

static int jffs2_do_readpage_nolock (struct inode *inode, struct page *pg)
{
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    unsigned char *pg_buf;
    int ret;

    jffs2_dbg(2, "%s(): ino #%lu, page at offset 0x%lx\n",
          __func__, inode->i_ino, pg->index << PAGE_CACHE_SHIFT);

    BUG_ON(!PageLocked(pg));

    pg_buf = kmap(pg);
    /* FIXME: Can kmap fail? */

    ret = jffs2_read_inode_range(c, f, pg_buf, pg->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE);

    if (ret) {
        ClearPageUptodate(pg);
        SetPageError(pg);
    } else {
        SetPageUptodate(pg);
        ClearPageError(pg);
    }

    flush_dcache_page(pg);
    kunmap(pg);

    jffs2_dbg(2, "readpage finished\n");
    return ret;
}

int jffs2_do_readpage_unlock(struct inode *inode, struct page *pg)
{
    int ret = jffs2_do_readpage_nolock(inode, pg);
    unlock_page(pg);
    return ret;
}


static int jffs2_readpage (struct file *filp, struct page *pg)
{
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(pg->mapping->host);
    int ret;

    mutex_lock(&f->sem);
    ret = jffs2_do_readpage_unlock(pg->mapping->host, pg);
    mutex_unlock(&f->sem);
    return ret;
}

static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata)
{
    struct page *pg;
    struct inode *inode = mapping->host;
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    struct jffs2_raw_inode ri;
    uint32_t alloc_len = 0;
    pgoff_t index = pos >> PAGE_CACHE_SHIFT;
    uint32_t pageofs = index << PAGE_CACHE_SHIFT;
    int ret = 0;

    jffs2_dbg(1, "%s()\n", __func__);

    if (pageofs > inode->i_size) {
        ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
                      ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
        if (ret)
            return ret;
    }

    mutex_lock(&f->sem);
    pg = grab_cache_page_write_begin(mapping, index, flags);
    if (!pg) {
        if (alloc_len)
            jffs2_complete_reservation(c);
        mutex_unlock(&f->sem);
        return -ENOMEM;
    }
    *pagep = pg;

    if (alloc_len) {
        /* Make new hole frag from old EOF to new page */
        struct jffs2_full_dnode *fn;

        jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
              (unsigned int)inode->i_size, pageofs);

        memset(&ri, 0, sizeof(ri));

        ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
        ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
        ri.totlen = cpu_to_je32(sizeof(ri));
        ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));

        ri.ino = cpu_to_je32(f->inocache->ino);
        ri.version = cpu_to_je32(++f->highest_version);
        ri.mode = cpu_to_jemode(inode->i_mode);
        ri.uid = cpu_to_je16(i_uid_read(inode));
        ri.gid = cpu_to_je16(i_gid_read(inode));
        ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
        ri.atime = ri.ctime = ri.mtime = cpu_to_je32(get_seconds());
        ri.offset = cpu_to_je32(inode->i_size);
        ri.dsize = cpu_to_je32(pageofs - inode->i_size);
        ri.csize = cpu_to_je32(0);
        ri.compr = JFFS2_COMPR_ZERO;
        ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
        ri.data_crc = cpu_to_je32(0);

        fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_NORMAL);

        if (IS_ERR(fn)) {
            ret = PTR_ERR(fn);
            jffs2_complete_reservation(c);
            goto out_page;
        }
        ret = jffs2_add_full_dnode_to_inode(c, f, fn);
        if (f->metadata) {
            jffs2_mark_node_obsolete(c, f->metadata->raw);
            jffs2_free_full_dnode(f->metadata);
            f->metadata = NULL;
        }
        if (ret) {
            jffs2_dbg(1, "Eep. add_full_dnode_to_inode() failed in write_begin, returned %d\n",
                  ret);
            jffs2_mark_node_obsolete(c, fn->raw);
            jffs2_free_full_dnode(fn);
            jffs2_complete_reservation(c);
            goto out_page;
        }
        jffs2_complete_reservation(c);
        inode->i_size = pageofs;
    }

    /*
     * Read in the page if it wasn't already present. Cannot optimize away
     * the whole page write case until jffs2_write_end can handle the
     * case of a short-copy.
     */
    if (!PageUptodate(pg)) {
        ret = jffs2_do_readpage_nolock(inode, pg);
        if (ret)
            goto out_page;
    }
    mutex_unlock(&f->sem);
    jffs2_dbg(1, "end write_begin(). pg->flags %lx\n", pg->flags);
    return ret;

out_page:
    unlock_page(pg);
    page_cache_release(pg);
    mutex_unlock(&f->sem);
    return ret;
}

static int jffs2_write_end(struct file *filp, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned copied,
            struct page *pg, void *fsdata)
{
    /* Actually commit the write from the page cache page we're looking at.
     * For now, we write the full page out each time. It sucks, but it's simple
     */
    struct inode *inode = mapping->host;
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
    struct jffs2_raw_inode *ri;
    unsigned start = pos & (PAGE_CACHE_SIZE - 1);
    unsigned end = start + copied;
    unsigned aligned_start = start & ~3;
    int ret = 0;
    uint32_t writtenlen = 0;

    jffs2_dbg(1, "%s(): ino #%lu, page at 0x%lx, range %d-%d, flags %lx\n",
          __func__, inode->i_ino, pg->index << PAGE_CACHE_SHIFT,
          start, end, pg->flags);

    /* We need to avoid deadlock with page_cache_read() in
       jffs2_garbage_collect_pass(). So the page must be
       up to date to prevent page_cache_read() from trying
       to re-lock it. */
    BUG_ON(!PageUptodate(pg));

    if (end == PAGE_CACHE_SIZE) {
        /* When writing out the end of a page, write out the
           _whole_ page. This helps to reduce the number of
           nodes in files which have many short writes, like
           syslog files. */
        aligned_start = 0;
    }

    ri = jffs2_alloc_raw_inode();

    if (!ri) {
        jffs2_dbg(1, "%s(): Allocation of raw inode failed\n",
              __func__);
        unlock_page(pg);
        page_cache_release(pg);
        return -ENOMEM;
    }

    /* Set the fields that the generic jffs2_write_inode_range() code can't find */
    ri->ino = cpu_to_je32(inode->i_ino);
    ri->mode = cpu_to_jemode(inode->i_mode);
    ri->uid = cpu_to_je16(i_uid_read(inode));
    ri->gid = cpu_to_je16(i_gid_read(inode));
    ri->isize = cpu_to_je32((uint32_t)inode->i_size);
    ri->atime = ri->ctime = ri->mtime = cpu_to_je32(get_seconds());

    /* In 2.4, it was already kmapped by generic_file_write(). Doesn't
       hurt to do it again. The alternative is ifdefs, which are ugly. */
    kmap(pg);

    ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + aligned_start,
                      (pg->index << PAGE_CACHE_SHIFT) + aligned_start,
                      end - aligned_start, &writtenlen);

    kunmap(pg);

    if (ret) {
        /* There was an error writing. */
        SetPageError(pg);
    }

    /* Adjust writtenlen for the padding we did, so we don't confuse our caller */
    writtenlen -= min(writtenlen, (start - aligned_start));

    if (writtenlen) {
        if (inode->i_size < pos + writtenlen) {
            inode->i_size = pos + writtenlen;
            inode->i_blocks = (inode->i_size + 511) >> 9;

            inode->i_ctime = inode->i_mtime = ITIME(je32_to_cpu(ri->ctime));
        }
    }

    jffs2_free_raw_inode(ri);

    if (start+writtenlen < end) {
        /* generic_file_write has written more to the page cache than we've
           actually written to the medium. Mark the page !Uptodate so that
           it gets reread */
        jffs2_dbg(1, "%s(): Not all bytes written. Marking page !uptodate\n",
            __func__);
        SetPageError(pg);
        ClearPageUptodate(pg);
    }

    jffs2_dbg(1, "%s() returning %d\n",
          __func__, writtenlen > 0 ? writtenlen : ret);
    unlock_page(pg);
    page_cache_release(pg);
    return writtenlen > 0 ? writtenlen : ret;
}