[GitHub/exynos8895/android_kernel_samsung_universal8895.git] / fs / f2fs / data.c

/*
 * fs/f2fs/data.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/prefetch.h>

#include "f2fs.h"
#include "node.h"
#include "segment.h"
#include <trace/events/f2fs.h>

/*
 * Lock ordering for the change of data block address:
 * ->data_page
 *  ->node_page
 *    update block addresses in the node page
 */
static void __set_data_blkaddr(struct dnode_of_data *dn, block_t new_addr)
{
        struct f2fs_node *rn;
        __le32 *addr_array;
        struct page *node_page = dn->node_page;
        unsigned int ofs_in_node = dn->ofs_in_node;

        wait_on_page_writeback(node_page);

        rn = (struct f2fs_node *)page_address(node_page);

        /* Get physical address of data block */
        addr_array = blkaddr_in_node(rn);
        addr_array[ofs_in_node] = cpu_to_le32(new_addr);
        set_page_dirty(node_page);
}

int reserve_new_block(struct dnode_of_data *dn)
{
        struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);

        if (is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC))
                return -EPERM;
        if (!inc_valid_block_count(sbi, dn->inode, 1))
                return -ENOSPC;

        __set_data_blkaddr(dn, NEW_ADDR);
        dn->data_blkaddr = NEW_ADDR;
        sync_inode_page(dn);
        return 0;
}

static int check_extent_cache(struct inode *inode, pgoff_t pgofs,
                                        struct buffer_head *bh_result)
{
        struct f2fs_inode_info *fi = F2FS_I(inode);
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        pgoff_t start_fofs, end_fofs;
        block_t start_blkaddr;

        read_lock(&fi->ext.ext_lock);
        if (fi->ext.len == 0) {
                read_unlock(&fi->ext.ext_lock);
                return 0;
        }

        sbi->total_hit_ext++;
        start_fofs = fi->ext.fofs;
        end_fofs = fi->ext.fofs + fi->ext.len - 1;
        start_blkaddr = fi->ext.blk_addr;

        if (pgofs >= start_fofs && pgofs <= end_fofs) {
                unsigned int blkbits = inode->i_sb->s_blocksize_bits;
                size_t count;

                clear_buffer_new(bh_result);
                map_bh(bh_result, inode->i_sb,
                                start_blkaddr + pgofs - start_fofs);
                count = end_fofs - pgofs + 1;
                if (count < (UINT_MAX >> blkbits))
                        bh_result->b_size = (count << blkbits);
                else
                        bh_result->b_size = UINT_MAX;

                sbi->read_hit_ext++;
                read_unlock(&fi->ext.ext_lock);
                return 1;
        }
        read_unlock(&fi->ext.ext_lock);
        return 0;
}

void update_extent_cache(block_t blk_addr, struct dnode_of_data *dn)
{
        struct f2fs_inode_info *fi = F2FS_I(dn->inode);
        pgoff_t fofs, start_fofs, end_fofs;
        block_t start_blkaddr, end_blkaddr;

        BUG_ON(blk_addr == NEW_ADDR);
        fofs = start_bidx_of_node(ofs_of_node(dn->node_page)) + dn->ofs_in_node;

        /* Update the page address in the parent node */
        __set_data_blkaddr(dn, blk_addr);

        write_lock(&fi->ext.ext_lock);

        start_fofs = fi->ext.fofs;
        end_fofs = fi->ext.fofs + fi->ext.len - 1;
        start_blkaddr = fi->ext.blk_addr;
        end_blkaddr = fi->ext.blk_addr + fi->ext.len - 1;

        /* Drop and initialize the matched extent */
        if (fi->ext.len == 1 && fofs == start_fofs)
                fi->ext.len = 0;

        /* Initial extent */
        if (fi->ext.len == 0) {
                if (blk_addr != NULL_ADDR) {
                        fi->ext.fofs = fofs;
                        fi->ext.blk_addr = blk_addr;
                        fi->ext.len = 1;
                }
                goto end_update;
        }

        /* Front merge */
        if (fofs == start_fofs - 1 && blk_addr == start_blkaddr - 1) {
                fi->ext.fofs--;
                fi->ext.blk_addr--;
                fi->ext.len++;
                goto end_update;
        }

        /* Back merge */
        if (fofs == end_fofs + 1 && blk_addr == end_blkaddr + 1) {
                fi->ext.len++;
                goto end_update;
        }

        /* Split the existing extent */
        if (fi->ext.len > 1 &&
                fofs >= start_fofs && fofs <= end_fofs) {
                if ((end_fofs - fofs) < (fi->ext.len >> 1)) {
                        fi->ext.len = fofs - start_fofs;
                } else {
                        fi->ext.fofs = fofs + 1;
                        fi->ext.blk_addr = start_blkaddr +
                                        fofs - start_fofs + 1;
                        fi->ext.len -= fofs - start_fofs + 1;
                }
                goto end_update;
        }
        write_unlock(&fi->ext.ext_lock);
        return;

end_update:
        write_unlock(&fi->ext.ext_lock);
        sync_inode_page(dn);
        return;
}

struct page *find_data_page(struct inode *inode, pgoff_t index)
{
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        struct address_space *mapping = inode->i_mapping;
        struct dnode_of_data dn;
        struct page *page;
        int err;

        page = find_get_page(mapping, index);
        if (page && PageUptodate(page))
                return page;
        f2fs_put_page(page, 0);

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
        if (err)
                return ERR_PTR(err);
        f2fs_put_dnode(&dn);

        if (dn.data_blkaddr == NULL_ADDR)
                return ERR_PTR(-ENOENT);

        /* By fallocate(), there is no cached page, but with NEW_ADDR */
        if (dn.data_blkaddr == NEW_ADDR)
                return ERR_PTR(-EINVAL);

        page = grab_cache_page(mapping, index);
        if (!page)
                return ERR_PTR(-ENOMEM);

        if (PageUptodate(page)) {
                unlock_page(page);
                return page;
        }

        err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
        wait_on_page_locked(page);
        if (!PageUptodate(page)) {
                f2fs_put_page(page, 0);
                return ERR_PTR(-EIO);
        }
        return page;
}

/*
 * If it tries to access a hole, return an error.
 * Because, the callers, functions in dir.c and GC, should be able to know
 * whether this page exists or not.
 */
struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
{
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        struct address_space *mapping = inode->i_mapping;
        struct dnode_of_data dn;
        struct page *page;
        int err;

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
        if (err)
                return ERR_PTR(err);
        f2fs_put_dnode(&dn);

        if (dn.data_blkaddr == NULL_ADDR)
                return ERR_PTR(-ENOENT);

        page = grab_cache_page(mapping, index);
        if (!page)
                return ERR_PTR(-ENOMEM);

        if (PageUptodate(page))
                return page;

        BUG_ON(dn.data_blkaddr == NEW_ADDR);
        BUG_ON(dn.data_blkaddr == NULL_ADDR);

        err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
        if (err)
                return ERR_PTR(err);

        lock_page(page);
        if (!PageUptodate(page)) {
                f2fs_put_page(page, 1);
                return ERR_PTR(-EIO);
        }
        return page;
}

/*
 * Caller ensures that this data page is never allocated.
 * A new zero-filled data page is allocated in the page cache.
 *
 * Also, caller should grab and release a mutex by calling mutex_lock_op() and
 * mutex_unlock_op().
 */
struct page *get_new_data_page(struct inode *inode, pgoff_t index,
                                                bool new_i_size)
{
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
        struct dnode_of_data dn;
        int err;

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, index, ALLOC_NODE);
        if (err)
                return ERR_PTR(err);

        if (dn.data_blkaddr == NULL_ADDR) {
                if (reserve_new_block(&dn)) {
                        f2fs_put_dnode(&dn);
                        return ERR_PTR(-ENOSPC);
                }
        }
        f2fs_put_dnode(&dn);

        page = grab_cache_page(mapping, index);
        if (!page)
                return ERR_PTR(-ENOMEM);

        if (PageUptodate(page))
                return page;

        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
                SetPageUptodate(page);
        } else {
                err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
                if (err)
                        return ERR_PTR(err);
                lock_page(page);
                if (!PageUptodate(page)) {
                        f2fs_put_page(page, 1);
                        return ERR_PTR(-EIO);
                }
        }

        if (new_i_size &&
                i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {
                i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
                mark_inode_dirty_sync(inode);
        }
        return page;
}

static void read_end_io(struct bio *bio, int err)
{
        const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
        struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;

        do {
                struct page *page = bvec->bv_page;

                if (--bvec >= bio->bi_io_vec)
                        prefetchw(&bvec->bv_page->flags);

                if (uptodate) {
                        SetPageUptodate(page);
                } else {
                        ClearPageUptodate(page);
                        SetPageError(page);
                }
                unlock_page(page);
        } while (bvec >= bio->bi_io_vec);
        kfree(bio->bi_private);
        bio_put(bio);
}

/*
 * Fill the locked page with data located in the block address.
 * Return unlocked page.
 */
int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
                                        block_t blk_addr, int type)
{
        struct block_device *bdev = sbi->sb->s_bdev;
        struct bio *bio;

        trace_f2fs_readpage(page, blk_addr, type);

        down_read(&sbi->bio_sem);

        /* Allocate a new bio */
        bio = f2fs_bio_alloc(bdev, 1);

        /* Initialize the bio */
        bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
        bio->bi_end_io = read_end_io;

        if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
                kfree(bio->bi_private);
                bio_put(bio);
                up_read(&sbi->bio_sem);
                f2fs_put_page(page, 1);
                return -EFAULT;
        }

        submit_bio(type, bio);
        up_read(&sbi->bio_sem);
        return 0;
}

/*
 * This function should be used by the data read flow only where it
 * does not check the "create" flag that indicates block allocation.
 * The reason for this special functionality is to exploit VFS readahead
 * mechanism.
 */
static int get_data_block_ro(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create)
{
        unsigned int blkbits = inode->i_sb->s_blocksize_bits;
        unsigned maxblocks = bh_result->b_size >> blkbits;
        struct dnode_of_data dn;
        pgoff_t pgofs;
        int err;

        /* Get the page offset from the block offset(iblock) */
        pgofs = (pgoff_t)(iblock >> (PAGE_CACHE_SHIFT - blkbits));

        if (check_extent_cache(inode, pgofs, bh_result)) {
                trace_f2fs_get_data_block(inode, iblock, bh_result, 0);
                return 0;
        }

        /* When reading holes, we need its node page */
        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, pgofs, LOOKUP_NODE_RA);
        if (err) {
                trace_f2fs_get_data_block(inode, iblock, bh_result, err);
                return (err == -ENOENT) ? 0 : err;
        }

        /* It does not support data allocation */
        BUG_ON(create);

        if (dn.data_blkaddr != NEW_ADDR && dn.data_blkaddr != NULL_ADDR) {
                int i;
                unsigned int end_offset;

                end_offset = IS_INODE(dn.node_page) ?
                                ADDRS_PER_INODE :
                                ADDRS_PER_BLOCK;

                clear_buffer_new(bh_result);

                /* Give more consecutive addresses for the read ahead */
                for (i = 0; i < end_offset - dn.ofs_in_node; i++)
                        if (((datablock_addr(dn.node_page,
                                                        dn.ofs_in_node + i))
                                != (dn.data_blkaddr + i)) || maxblocks == i)
                                break;
                map_bh(bh_result, inode->i_sb, dn.data_blkaddr);
                bh_result->b_size = (i << blkbits);
        }
        f2fs_put_dnode(&dn);
        trace_f2fs_get_data_block(inode, iblock, bh_result, 0);
        return 0;
}

static int f2fs_read_data_page(struct file *file, struct page *page)
{
        return mpage_readpage(page, get_data_block_ro);
}

static int f2fs_read_data_pages(struct file *file,
                        struct address_space *mapping,
                        struct list_head *pages, unsigned nr_pages)
{
        return mpage_readpages(mapping, pages, nr_pages, get_data_block_ro);
}

int do_write_data_page(struct page *page)
{
        struct inode *inode = page->mapping->host;
        block_t old_blk_addr, new_blk_addr;
        struct dnode_of_data dn;
        int err = 0;

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
        if (err)
                return err;

        old_blk_addr = dn.data_blkaddr;

        /* This page is already truncated */
        if (old_blk_addr == NULL_ADDR)
                goto out_writepage;

        set_page_writeback(page);

        /*
         * If current allocation needs SSR,
         * it had better in-place writes for updated data.
         */
        if (old_blk_addr != NEW_ADDR && !is_cold_data(page) &&
                                need_inplace_update(inode)) {
                rewrite_data_page(F2FS_SB(inode->i_sb), page,
                                                old_blk_addr);
        } else {
                write_data_page(inode, page, &dn,
                                old_blk_addr, &new_blk_addr);
                update_extent_cache(new_blk_addr, &dn);
        }
out_writepage:
        f2fs_put_dnode(&dn);
        return err;
}

static int f2fs_write_data_page(struct page *page,
                                        struct writeback_control *wbc)
{
        struct inode *inode = page->mapping->host;
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        loff_t i_size = i_size_read(inode);
        const pgoff_t end_index = ((unsigned long long) i_size)
                                                        >> PAGE_CACHE_SHIFT;
        unsigned offset;
        bool need_balance_fs = false;
        int err = 0;

        if (page->index < end_index)
                goto write;

        /*
         * If the offset is out-of-range of file size,
         * this page does not have to be written to disk.
         */
        offset = i_size & (PAGE_CACHE_SIZE - 1);
        if ((page->index >= end_index + 1) || !offset) {
                if (S_ISDIR(inode->i_mode)) {
                        dec_page_count(sbi, F2FS_DIRTY_DENTS);
                        inode_dec_dirty_dents(inode);
                }
                goto out;
        }

        zero_user_segment(page, offset, PAGE_CACHE_SIZE);
write:
        if (sbi->por_doing) {
                err = AOP_WRITEPAGE_ACTIVATE;
                goto redirty_out;
        }

        /* Dentry blocks are controlled by checkpoint */
        if (S_ISDIR(inode->i_mode)) {
                dec_page_count(sbi, F2FS_DIRTY_DENTS);
                inode_dec_dirty_dents(inode);
                err = do_write_data_page(page);
        } else {
                int ilock = mutex_lock_op(sbi);
                err = do_write_data_page(page);
                mutex_unlock_op(sbi, ilock);
                need_balance_fs = true;
        }
        if (err == -ENOENT)
                goto out;
        else if (err)
                goto redirty_out;

        if (wbc->for_reclaim)
                f2fs_submit_bio(sbi, DATA, true);

        clear_cold_data(page);
out:
        unlock_page(page);
        if (need_balance_fs)
                f2fs_balance_fs(sbi);
        return 0;

redirty_out:
        wbc->pages_skipped++;
        set_page_dirty(page);
        return err;
}

#define MAX_DESIRED_PAGES_WP    4096

static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
                        void *data)
{
        struct address_space *mapping = data;
        int ret = mapping->a_ops->writepage(page, wbc);
        mapping_set_error(mapping, ret);
        return ret;
}

static int f2fs_write_data_pages(struct address_space *mapping,
                            struct writeback_control *wbc)
{
        struct inode *inode = mapping->host;
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        int ret;
        long excess_nrtw = 0, desired_nrtw;

        /* deal with chardevs and other special file */
        if (!mapping->a_ops->writepage)
                return 0;

        if (wbc->nr_to_write < MAX_DESIRED_PAGES_WP) {
                desired_nrtw = MAX_DESIRED_PAGES_WP;
                excess_nrtw = desired_nrtw - wbc->nr_to_write;
                wbc->nr_to_write = desired_nrtw;
        }

        if (!S_ISDIR(inode->i_mode))
                mutex_lock(&sbi->writepages);
        ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
        if (!S_ISDIR(inode->i_mode))
                mutex_unlock(&sbi->writepages);
        f2fs_submit_bio(sbi, DATA, (wbc->sync_mode == WB_SYNC_ALL));

        remove_dirty_dir_inode(inode);

        wbc->nr_to_write -= excess_nrtw;
        return ret;
}

static int f2fs_write_begin(struct file *file, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned flags,
                struct page **pagep, void **fsdata)
{
        struct inode *inode = mapping->host;
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        struct page *page;
        pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
        struct dnode_of_data dn;
        int err = 0;
        int ilock;

        /* for nobh_write_end */
        *fsdata = NULL;

        f2fs_balance_fs(sbi);

        page = grab_cache_page_write_begin(mapping, index, flags);
        if (!page)
                return -ENOMEM;
        *pagep = page;

        ilock = mutex_lock_op(sbi);

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, index, ALLOC_NODE);
        if (err)
                goto err;

        if (dn.data_blkaddr == NULL_ADDR)
                err = reserve_new_block(&dn);

        f2fs_put_dnode(&dn);
        if (err)
                goto err;

        mutex_unlock_op(sbi, ilock);

        if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
                return 0;

        if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
                unsigned start = pos & (PAGE_CACHE_SIZE - 1);
                unsigned end = start + len;

                /* Reading beyond i_size is simple: memset to zero */
                zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
                goto out;
        }

        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
        } else {
                err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
                if (err)
                        return err;
                lock_page(page);
                if (!PageUptodate(page)) {
                        f2fs_put_page(page, 1);
                        return -EIO;
                }
        }
out:
        SetPageUptodate(page);
        clear_cold_data(page);
        return 0;

err:
        mutex_unlock_op(sbi, ilock);
        f2fs_put_page(page, 1);
        return err;
}

static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
                const struct iovec *iov, loff_t offset, unsigned long nr_segs)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;

        if (rw == WRITE)
                return 0;

        /* Needs synchronization with the cleaner */
        return blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
                                                  get_data_block_ro);
}

static void f2fs_invalidate_data_page(struct page *page, unsigned long offset)
{
        struct inode *inode = page->mapping->host;
        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
        if (S_ISDIR(inode->i_mode) && PageDirty(page)) {
                dec_page_count(sbi, F2FS_DIRTY_DENTS);
                inode_dec_dirty_dents(inode);
        }
        ClearPagePrivate(page);
}

static int f2fs_release_data_page(struct page *page, gfp_t wait)
{
        ClearPagePrivate(page);
        return 1;
}

static int f2fs_set_data_page_dirty(struct page *page)
{
        struct address_space *mapping = page->mapping;
        struct inode *inode = mapping->host;

        SetPageUptodate(page);
        if (!PageDirty(page)) {
                __set_page_dirty_nobuffers(page);
                set_dirty_dir_page(inode, page);
                return 1;
        }
        return 0;
}

static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
{
        return generic_block_bmap(mapping, block, get_data_block_ro);
}

const struct address_space_operations f2fs_dblock_aops = {
        .readpage       = f2fs_read_data_page,
        .readpages      = f2fs_read_data_pages,
        .writepage      = f2fs_write_data_page,
        .writepages     = f2fs_write_data_pages,
        .write_begin    = f2fs_write_begin,
        .write_end      = nobh_write_end,
        .set_page_dirty = f2fs_set_data_page_dirty,
        .invalidatepage = f2fs_invalidate_data_page,
        .releasepage    = f2fs_release_data_page,
        .direct_IO      = f2fs_direct_IO,
        .bmap           = f2fs_bmap,
};