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[linux-2.6] / fs / ocfs2 / aops.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 * This program 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; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <asm/byteorder.h>

#define MLOG_MASK_PREFIX ML_FILE_IO
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "aops.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "file.h"
#include "inode.h"
#include "journal.h"
#include "super.h"
#include "symlink.h"

#include "buffer_head_io.h"

static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
                                   struct buffer_head *bh_result, int create)
{
        int err = -EIO;
        int status;
        struct ocfs2_dinode *fe = NULL;
        struct buffer_head *bh = NULL;
        struct buffer_head *buffer_cache_bh = NULL;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        void *kaddr;

        mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
                   (unsigned long long)iblock, bh_result, create);

        BUG_ON(ocfs2_inode_is_fast_symlink(inode));

        if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
                mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
                     (unsigned long long)iblock);
                goto bail;
        }

        status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
                                  OCFS2_I(inode)->ip_blkno,
                                  &bh, OCFS2_BH_CACHED, inode);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }
        fe = (struct ocfs2_dinode *) bh->b_data;

        if (!OCFS2_IS_VALID_DINODE(fe)) {
                mlog(ML_ERROR, "Invalid dinode #%"MLFu64": signature = %.*s\n",
                     fe->i_blkno, 7, fe->i_signature);
                goto bail;
        }

        if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
                                                    le32_to_cpu(fe->i_clusters))) {
                mlog(ML_ERROR, "block offset is outside the allocated size: "
                     "%llu\n", (unsigned long long)iblock);
                goto bail;
        }

        /* We don't use the page cache to create symlink data, so if
         * need be, copy it over from the buffer cache. */
        if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
                u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
                            iblock;
                buffer_cache_bh = sb_getblk(osb->sb, blkno);
                if (!buffer_cache_bh) {
                        mlog(ML_ERROR, "couldn't getblock for symlink!\n");
                        goto bail;
                }

                /* we haven't locked out transactions, so a commit
                 * could've happened. Since we've got a reference on
                 * the bh, even if it commits while we're doing the
                 * copy, the data is still good. */
                if (buffer_jbd(buffer_cache_bh)
                    && ocfs2_inode_is_new(inode)) {
                        kaddr = kmap_atomic(bh_result->b_page, KM_USER0);
                        if (!kaddr) {
                                mlog(ML_ERROR, "couldn't kmap!\n");
                                goto bail;
                        }
                        memcpy(kaddr + (bh_result->b_size * iblock),
                               buffer_cache_bh->b_data,
                               bh_result->b_size);
                        kunmap_atomic(kaddr, KM_USER0);
                        set_buffer_uptodate(bh_result);
                }
                brelse(buffer_cache_bh);
        }

        map_bh(bh_result, inode->i_sb,
               le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);

        err = 0;

bail:
        if (bh)
                brelse(bh);

        mlog_exit(err);
        return err;
}

static int ocfs2_get_block(struct inode *inode, sector_t iblock,
                           struct buffer_head *bh_result, int create)
{
        int err = 0;
        u64 p_blkno, past_eof;

        mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
                   (unsigned long long)iblock, bh_result, create);

        if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE)
                mlog(ML_NOTICE, "get_block on system inode 0x%p (%lu)\n",
                     inode, inode->i_ino);

        if (S_ISLNK(inode->i_mode)) {
                /* this always does I/O for some reason. */
                err = ocfs2_symlink_get_block(inode, iblock, bh_result, create);
                goto bail;
        }

        /* this can happen if another node truncs after our extend! */
        spin_lock(&OCFS2_I(inode)->ip_lock);
        if (iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
                                               OCFS2_I(inode)->ip_clusters))
                err = -EIO;
        spin_unlock(&OCFS2_I(inode)->ip_lock);
        if (err)
                goto bail;

        err = ocfs2_extent_map_get_blocks(inode, iblock, 1, &p_blkno,
                                          NULL);
        if (err) {
                mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
                     "%"MLFu64", NULL)\n", err, inode,
                     (unsigned long long)iblock, p_blkno);
                goto bail;
        }

        map_bh(bh_result, inode->i_sb, p_blkno);

        if (bh_result->b_blocknr == 0) {
                err = -EIO;
                mlog(ML_ERROR, "iblock = %llu p_blkno = %"MLFu64" "
                     "blkno=(%"MLFu64")\n", (unsigned long long)iblock,
                     p_blkno, OCFS2_I(inode)->ip_blkno);
        }

        past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
        mlog(0, "Inode %lu, past_eof = %"MLFu64"\n", inode->i_ino, past_eof);

        if (create && (iblock >= past_eof))
                set_buffer_new(bh_result);

bail:
        if (err < 0)
                err = -EIO;

        mlog_exit(err);
        return err;
}

static int ocfs2_readpage(struct file *file, struct page *page)
{
        struct inode *inode = page->mapping->host;
        loff_t start = (loff_t)page->index << PAGE_CACHE_SHIFT;
        int ret, unlock = 1;

        mlog_entry("(0x%p, %lu)\n", file, (page ? page->index : 0));

        ret = ocfs2_meta_lock_with_page(inode, NULL, NULL, 0, page);
        if (ret != 0) {
                if (ret == AOP_TRUNCATED_PAGE)
                        unlock = 0;
                mlog_errno(ret);
                goto out;
        }

        down_read(&OCFS2_I(inode)->ip_alloc_sem);

        /*
         * i_size might have just been updated as we grabed the meta lock.  We
         * might now be discovering a truncate that hit on another node.
         * block_read_full_page->get_block freaks out if it is asked to read
         * beyond the end of a file, so we check here.  Callers
         * (generic_file_read, fault->nopage) are clever enough to check i_size
         * and notice that the page they just read isn't needed.
         *
         * XXX sys_readahead() seems to get that wrong?
         */
        if (start >= i_size_read(inode)) {
                char *addr = kmap(page);
                memset(addr, 0, PAGE_SIZE);
                flush_dcache_page(page);
                kunmap(page);
                SetPageUptodate(page);
                ret = 0;
                goto out_alloc;
        }

        ret = ocfs2_data_lock_with_page(inode, 0, page);
        if (ret != 0) {
                if (ret == AOP_TRUNCATED_PAGE)
                        unlock = 0;
                mlog_errno(ret);
                goto out_alloc;
        }

        ret = block_read_full_page(page, ocfs2_get_block);
        unlock = 0;

        ocfs2_data_unlock(inode, 0);
out_alloc:
        up_read(&OCFS2_I(inode)->ip_alloc_sem);
        ocfs2_meta_unlock(inode, 0);
out:
        if (unlock)
                unlock_page(page);
        mlog_exit(ret);
        return ret;
}

/* Note: Because we don't support holes, our allocation has
 * already happened (allocation writes zeros to the file data)
 * so we don't have to worry about ordered writes in
 * ocfs2_writepage.
 *
 * ->writepage is called during the process of invalidating the page cache
 * during blocked lock processing.  It can't block on any cluster locks
 * to during block mapping.  It's relying on the fact that the block
 * mapping can't have disappeared under the dirty pages that it is
 * being asked to write back.
 */
static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
{
        int ret;

        mlog_entry("(0x%p)\n", page);

        ret = block_write_full_page(page, ocfs2_get_block, wbc);

        mlog_exit(ret);

        return ret;
}

/*
 * ocfs2_prepare_write() can be an outer-most ocfs2 call when it is called
 * from loopback.  It must be able to perform its own locking around
 * ocfs2_get_block().
 */
int ocfs2_prepare_write(struct file *file, struct page *page,
                        unsigned from, unsigned to)
{
        struct inode *inode = page->mapping->host;
        int ret;

        mlog_entry("(0x%p, 0x%p, %u, %u)\n", file, page, from, to);

        ret = ocfs2_meta_lock_with_page(inode, NULL, NULL, 0, page);
        if (ret != 0) {
                mlog_errno(ret);
                goto out;
        }

        down_read(&OCFS2_I(inode)->ip_alloc_sem);

        ret = block_prepare_write(page, from, to, ocfs2_get_block);

        up_read(&OCFS2_I(inode)->ip_alloc_sem);

        ocfs2_meta_unlock(inode, 0);
out:
        mlog_exit(ret);
        return ret;
}

/* Taken from ext3. We don't necessarily need the full blown
 * functionality yet, but IMHO it's better to cut and paste the whole
 * thing so we can avoid introducing our own bugs (and easily pick up
 * their fixes when they happen) --Mark */
static int walk_page_buffers(   handle_t *handle,
                                struct buffer_head *head,
                                unsigned from,
                                unsigned to,
                                int *partial,
                                int (*fn)(      handle_t *handle,
                                                struct buffer_head *bh))
{
        struct buffer_head *bh;
        unsigned block_start, block_end;
        unsigned blocksize = head->b_size;
        int err, ret = 0;
        struct buffer_head *next;

        for (   bh = head, block_start = 0;
                ret == 0 && (bh != head || !block_start);
                block_start = block_end, bh = next)
        {
                next = bh->b_this_page;
                block_end = block_start + blocksize;
                if (block_end <= from || block_start >= to) {
                        if (partial && !buffer_uptodate(bh))
                                *partial = 1;
                        continue;
                }
                err = (*fn)(handle, bh);
                if (!ret)
                        ret = err;
        }
        return ret;
}

struct ocfs2_journal_handle *ocfs2_start_walk_page_trans(struct inode *inode,
                                                         struct page *page,
                                                         unsigned from,
                                                         unsigned to)
{
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct ocfs2_journal_handle *handle = NULL;
        int ret = 0;

        handle = ocfs2_start_trans(osb, NULL, OCFS2_INODE_UPDATE_CREDITS);
        if (!handle) {
                ret = -ENOMEM;
                mlog_errno(ret);
                goto out;
        }

        if (ocfs2_should_order_data(inode)) {
                ret = walk_page_buffers(handle->k_handle,
                                        page_buffers(page),
                                        from, to, NULL,
                                        ocfs2_journal_dirty_data);
                if (ret < 0) 
                        mlog_errno(ret);
        }
out:
        if (ret) {
                if (handle)
                        ocfs2_commit_trans(handle);
                handle = ERR_PTR(ret);
        }
        return handle;
}

static int ocfs2_commit_write(struct file *file, struct page *page,
                              unsigned from, unsigned to)
{
        int ret, extending = 0, locklevel = 0;
        loff_t new_i_size;
        struct buffer_head *di_bh = NULL;
        struct inode *inode = page->mapping->host;
        struct ocfs2_journal_handle *handle = NULL;

        mlog_entry("(0x%p, 0x%p, %u, %u)\n", file, page, from, to);

        /* NOTE: ocfs2_file_aio_write has ensured that it's safe for
         * us to sample inode->i_size here without the metadata lock:
         *
         * 1) We're currently holding the inode alloc lock, so no
         *    nodes can change it underneath us.
         *
         * 2) We've had to take the metadata lock at least once
         *    already to check for extending writes, hence insuring
         *    that our current copy is also up to date.
         */
        new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
        if (new_i_size > i_size_read(inode)) {
                extending = 1;
                locklevel = 1;
        }

        ret = ocfs2_meta_lock_with_page(inode, NULL, &di_bh, locklevel, page);
        if (ret != 0) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_data_lock_with_page(inode, 1, page);
        if (ret != 0) {
                mlog_errno(ret);
                goto out_unlock_meta;
        }

        if (extending) {
                handle = ocfs2_start_walk_page_trans(inode, page, from, to);
                if (IS_ERR(handle)) {
                        ret = PTR_ERR(handle);
                        handle = NULL;
                        goto out_unlock_data;
                }

                /* Mark our buffer early. We'd rather catch this error up here
                 * as opposed to after a successful commit_write which would
                 * require us to set back inode->i_size. */
                ret = ocfs2_journal_access(handle, inode, di_bh,
                                           OCFS2_JOURNAL_ACCESS_WRITE);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out_commit;
                }
        }

        /* might update i_size */
        ret = generic_commit_write(file, page, from, to);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_commit;
        }

        if (extending) {
                loff_t size = (u64) i_size_read(inode);
                struct ocfs2_dinode *di =
                        (struct ocfs2_dinode *)di_bh->b_data;

                /* ocfs2_mark_inode_dirty is too heavy to use here. */
                inode->i_blocks = ocfs2_align_bytes_to_sectors(size);
                inode->i_ctime = inode->i_mtime = CURRENT_TIME;

                di->i_size = cpu_to_le64(size);
                di->i_ctime = di->i_mtime = 
                                cpu_to_le64(inode->i_mtime.tv_sec);
                di->i_ctime_nsec = di->i_mtime_nsec = 
                                cpu_to_le32(inode->i_mtime.tv_nsec);

                ret = ocfs2_journal_dirty(handle, di_bh);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out_commit;
                }
        }

        BUG_ON(extending && (i_size_read(inode) != new_i_size));

out_commit:
        if (handle)
                ocfs2_commit_trans(handle);
out_unlock_data:
        ocfs2_data_unlock(inode, 1);
out_unlock_meta:
        ocfs2_meta_unlock(inode, locklevel);
out:
        if (di_bh)
                brelse(di_bh);

        mlog_exit(ret);
        return ret;
}

static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
{
        sector_t status;
        u64 p_blkno = 0;
        int err = 0;
        struct inode *inode = mapping->host;

        mlog_entry("(block = %llu)\n", (unsigned long long)block);

        /* We don't need to lock journal system files, since they aren't
         * accessed concurrently from multiple nodes.
         */
        if (!INODE_JOURNAL(inode)) {
                err = ocfs2_meta_lock(inode, NULL, NULL, 0);
                if (err) {
                        if (err != -ENOENT)
                                mlog_errno(err);
                        goto bail;
                }
                down_read(&OCFS2_I(inode)->ip_alloc_sem);
        }

        err = ocfs2_extent_map_get_blocks(inode, block, 1, &p_blkno,
                                          NULL);

        if (!INODE_JOURNAL(inode)) {
                up_read(&OCFS2_I(inode)->ip_alloc_sem);
                ocfs2_meta_unlock(inode, 0);
        }

        if (err) {
                mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
                     (unsigned long long)block);
                mlog_errno(err);
                goto bail;
        }


bail:
        status = err ? 0 : p_blkno;

        mlog_exit((int)status);

        return status;
}

/*
 * TODO: Make this into a generic get_blocks function.
 *
 * From do_direct_io in direct-io.c:
 *  "So what we do is to permit the ->get_blocks function to populate
 *   bh.b_size with the size of IO which is permitted at this offset and
 *   this i_blkbits."
 *
 * This function is called directly from get_more_blocks in direct-io.c.
 *
 * called like this: dio->get_blocks(dio->inode, fs_startblk,
 *                                      fs_count, map_bh, dio->rw == WRITE);
 */
static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
                                     unsigned long max_blocks,
                                     struct buffer_head *bh_result, int create)
{
        int ret;
        u64 vbo_max; /* file offset, max_blocks from iblock */
        u64 p_blkno;
        int contig_blocks;
        unsigned char blocksize_bits;

        if (!inode || !bh_result) {
                mlog(ML_ERROR, "inode or bh_result is null\n");
                return -EIO;
        }

        blocksize_bits = inode->i_sb->s_blocksize_bits;

        /* This function won't even be called if the request isn't all
         * nicely aligned and of the right size, so there's no need
         * for us to check any of that. */

        vbo_max = ((u64)iblock + max_blocks) << blocksize_bits;

        spin_lock(&OCFS2_I(inode)->ip_lock);
        if ((iblock + max_blocks) >
            ocfs2_clusters_to_blocks(inode->i_sb,
                                     OCFS2_I(inode)->ip_clusters)) {
                spin_unlock(&OCFS2_I(inode)->ip_lock);
                ret = -EIO;
                goto bail;
        }
        spin_unlock(&OCFS2_I(inode)->ip_lock);

        /* This figures out the size of the next contiguous block, and
         * our logical offset */
        ret = ocfs2_extent_map_get_blocks(inode, iblock, 1, &p_blkno,
                                          &contig_blocks);
        if (ret) {
                mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
                     (unsigned long long)iblock);
                ret = -EIO;
                goto bail;
        }

        map_bh(bh_result, inode->i_sb, p_blkno);

        /* make sure we don't map more than max_blocks blocks here as
           that's all the kernel will handle at this point. */
        if (max_blocks < contig_blocks)
                contig_blocks = max_blocks;
        bh_result->b_size = contig_blocks << blocksize_bits;
bail:
        return ret;
}

/* 
 * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
 * particularly interested in the aio/dio case.  Like the core uses
 * i_alloc_sem, we use the rw_lock DLM lock to protect io on one node from
 * truncation on another.
 */
static void ocfs2_dio_end_io(struct kiocb *iocb,
                             loff_t offset,
                             ssize_t bytes,
                             void *private)
{
        struct inode *inode = iocb->ki_filp->f_dentry->d_inode;

        /* this io's submitter should not have unlocked this before we could */
        BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
        ocfs2_iocb_clear_rw_locked(iocb);
        up_read(&inode->i_alloc_sem);
        ocfs2_rw_unlock(inode, 0);
}

static ssize_t ocfs2_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_dentry->d_inode->i_mapping->host;
        int ret;

        mlog_entry_void();
        ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
                                            inode->i_sb->s_bdev, iov, offset,
                                            nr_segs, 
                                            ocfs2_direct_IO_get_blocks,
                                            ocfs2_dio_end_io);
        mlog_exit(ret);
        return ret;
}

struct address_space_operations ocfs2_aops = {
        .readpage       = ocfs2_readpage,
        .writepage      = ocfs2_writepage,
        .prepare_write  = ocfs2_prepare_write,
        .commit_write   = ocfs2_commit_write,
        .bmap           = ocfs2_bmap,
        .sync_page      = block_sync_page,
        .direct_IO      = ocfs2_direct_IO
};