/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * 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/filelock.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(const struct kiocb *iocb,
                           struct address_space *mapping,
                           loff_t pos, unsigned len, unsigned copied,
                           struct folio *folio, void *fsdata);
static int jffs2_write_begin(const struct kiocb *iocb,
                             struct address_space *mapping,
                             loff_t pos, unsigned len,
                             struct folio **foliop, void **fsdata);
static int jffs2_read_folio(struct file *filp, struct folio *folio);

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 = file_write_and_wait_range(filp, start, end);
        if (ret)
                return ret;

        inode_lock(inode);
        /* Trigger GC to flush any pending writes for this inode */
        jffs2_flush_wbuf_gc(c, inode->i_ino);
        inode_unlock(inode);

        return 0;
}

const struct file_operations jffs2_file_operations =
{
        .llseek =       generic_file_llseek,
        .open =         generic_file_open,
        .read_iter =    generic_file_read_iter,
        .write_iter =   generic_file_write_iter,
        .unlocked_ioctl=jffs2_ioctl,
        .mmap_prepare = generic_file_readonly_mmap_prepare,
        .fsync =        jffs2_fsync,
        .splice_read =  filemap_splice_read,
        .splice_write = iter_file_splice_write,
        .setlease =     generic_setlease,
};

/* jffs2_file_inode_operations */

const struct inode_operations jffs2_file_inode_operations =
{
        .get_inode_acl =        jffs2_get_acl,
        .set_acl =      jffs2_set_acl,
        .setattr =      jffs2_setattr,
        .listxattr =    jffs2_listxattr,
};

const struct address_space_operations jffs2_file_address_operations =
{
        .read_folio =   jffs2_read_folio,
        .write_begin =  jffs2_write_begin,
        .write_end =    jffs2_write_end,
};

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

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

        BUG_ON(!folio_test_locked(folio));

        kaddr = kmap_local_folio(folio, 0);
        ret = jffs2_read_inode_range(c, f, kaddr, folio->index << PAGE_SHIFT,
                                     PAGE_SIZE);
        kunmap_local(kaddr);

        if (!ret)
                folio_mark_uptodate(folio);

        flush_dcache_folio(folio);

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

int __jffs2_read_folio(struct file *file, struct folio *folio)
{
        int ret = jffs2_do_readpage_nolock(folio->mapping->host, folio);
        folio_unlock(folio);
        return ret;
}

static int jffs2_read_folio(struct file *file, struct folio *folio)
{
        struct jffs2_inode_info *f = JFFS2_INODE_INFO(folio->mapping->host);
        int ret;

        mutex_lock(&f->sem);
        ret = __jffs2_read_folio(file, folio);
        mutex_unlock(&f->sem);
        return ret;
}

static int jffs2_write_begin(const struct kiocb *iocb,
                             struct address_space *mapping,
                             loff_t pos, unsigned len,
                             struct folio **foliop, void **fsdata)
{
        struct folio *folio;
        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);
        pgoff_t index = pos >> PAGE_SHIFT;
        int ret = 0;

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

        if (pos > inode->i_size) {
                /* Make new hole frag from old EOF to new position */
                struct jffs2_raw_inode ri;
                struct jffs2_full_dnode *fn;
                uint32_t alloc_len;

                jffs2_dbg(1, "Writing new hole frag 0x%x-0x%x between current EOF and new position\n",
                          (unsigned int)inode->i_size, (uint32_t)pos);

                ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
                                          ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
                if (ret)
                        goto out_err;

                mutex_lock(&f->sem);
                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((uint32_t)pos);
                ri.atime = ri.ctime = ri.mtime = cpu_to_je32(JFFS2_NOW());
                ri.offset = cpu_to_je32(inode->i_size);
                ri.dsize = cpu_to_je32((uint32_t)pos - 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);
                        mutex_unlock(&f->sem);
                        goto out_err;
                }
                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);
                        mutex_unlock(&f->sem);
                        goto out_err;
                }
                jffs2_complete_reservation(c);
                inode->i_size = pos;
                mutex_unlock(&f->sem);
        }

        /*
         * While getting a page and reading data in, lock c->alloc_sem until
         * the page is Uptodate. Otherwise GC task may attempt to read the same
         * page in read_cache_page(), which causes a deadlock.
         */
        mutex_lock(&c->alloc_sem);
        folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
                        mapping_gfp_mask(mapping));
        if (IS_ERR(folio)) {
                ret = PTR_ERR(folio);
                goto release_sem;
        }
        *foliop = folio;

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

release_sem:
        mutex_unlock(&c->alloc_sem);
out_err:
        return ret;
}

static int jffs2_write_end(const struct kiocb *iocb,
                           struct address_space *mapping,
                           loff_t pos, unsigned len, unsigned copied,
                           struct folio *folio, 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_SIZE - 1);
        unsigned end = start + copied;
        unsigned aligned_start = start & ~3;
        int ret = 0;
        uint32_t writtenlen = 0;
        void *buf;

        jffs2_dbg(1, "%s(): ino #%lu, page at 0x%llx, range %d-%d, flags %lx\n",
                  __func__, inode->i_ino, folio_pos(folio),
                  start, end, folio->flags.f);

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

        if (end == PAGE_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__);
                folio_unlock(folio);
                folio_put(folio);
                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(JFFS2_NOW());

        buf = kmap_local_folio(folio, aligned_start);
        ret = jffs2_write_inode_range(c, f, ri, buf,
                                      folio_pos(folio) + aligned_start,
                                      end - aligned_start, &writtenlen);
        kunmap_local(buf);

        if (ret)
                mapping_set_error(mapping, ret);

        /* 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_set_mtime_to_ts(inode,
                                              inode_set_ctime_to_ts(inode, 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__);
                folio_clear_uptodate(folio);
        }

        jffs2_dbg(1, "%s() returning %d\n",
                  __func__, writtenlen > 0 ? writtenlen : ret);
        folio_unlock(folio);
        folio_put(folio);
        return writtenlen > 0 ? writtenlen : ret;
}