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343 lines
8.6 KiB
343 lines
8.6 KiB
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* io.c
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*
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* Buffer cache handling
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*
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* Copyright (C) 2002, 2004 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/highmem.h>
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#include <cluster/masklog.h>
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#include "ocfs2.h"
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#include "alloc.h"
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#include "inode.h"
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#include "journal.h"
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#include "uptodate.h"
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#include "buffer_head_io.h"
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int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
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struct inode *inode)
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{
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int ret = 0;
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mlog_entry("(bh->b_blocknr = %llu, inode=%p)\n",
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(unsigned long long)bh->b_blocknr, inode);
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BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
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BUG_ON(buffer_jbd(bh));
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/* No need to check for a soft readonly file system here. non
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* journalled writes are only ever done on system files which
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* can get modified during recovery even if read-only. */
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if (ocfs2_is_hard_readonly(osb)) {
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ret = -EROFS;
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goto out;
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}
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mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
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lock_buffer(bh);
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set_buffer_uptodate(bh);
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/* remove from dirty list before I/O. */
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clear_buffer_dirty(bh);
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get_bh(bh); /* for end_buffer_write_sync() */
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bh->b_end_io = end_buffer_write_sync;
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submit_bh(WRITE, bh);
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wait_on_buffer(bh);
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if (buffer_uptodate(bh)) {
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ocfs2_set_buffer_uptodate(inode, bh);
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} else {
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/* We don't need to remove the clustered uptodate
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* information for this bh as it's not marked locally
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* uptodate. */
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ret = -EIO;
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put_bh(bh);
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}
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mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
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out:
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mlog_exit(ret);
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return ret;
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}
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int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr,
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struct buffer_head *bhs[], int flags,
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struct inode *inode)
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{
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int status = 0;
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struct super_block *sb;
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int i, ignore_cache = 0;
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struct buffer_head *bh;
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mlog_entry("(block=(%llu), nr=(%d), flags=%d, inode=%p)\n",
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(unsigned long long)block, nr, flags, inode);
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BUG_ON((flags & OCFS2_BH_READAHEAD) &&
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(!inode || !(flags & OCFS2_BH_CACHED)));
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if (osb == NULL || osb->sb == NULL || bhs == NULL) {
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status = -EINVAL;
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mlog_errno(status);
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goto bail;
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}
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if (nr < 0) {
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mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
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status = -EINVAL;
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mlog_errno(status);
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goto bail;
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}
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if (nr == 0) {
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mlog(ML_BH_IO, "No buffers will be read!\n");
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status = 0;
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goto bail;
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}
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sb = osb->sb;
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if (flags & OCFS2_BH_CACHED && !inode)
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flags &= ~OCFS2_BH_CACHED;
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if (inode)
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mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
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for (i = 0 ; i < nr ; i++) {
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if (bhs[i] == NULL) {
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bhs[i] = sb_getblk(sb, block++);
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if (bhs[i] == NULL) {
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if (inode)
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mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
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status = -EIO;
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mlog_errno(status);
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goto bail;
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}
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}
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bh = bhs[i];
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ignore_cache = 0;
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/* There are three read-ahead cases here which we need to
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* be concerned with. All three assume a buffer has
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* previously been submitted with OCFS2_BH_READAHEAD
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* and it hasn't yet completed I/O.
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*
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* 1) The current request is sync to disk. This rarely
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* happens these days, and never when performance
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* matters - the code can just wait on the buffer
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* lock and re-submit.
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*
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* 2) The current request is cached, but not
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* readahead. ocfs2_buffer_uptodate() will return
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* false anyway, so we'll wind up waiting on the
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* buffer lock to do I/O. We re-check the request
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* with after getting the lock to avoid a re-submit.
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*
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* 3) The current request is readahead (and so must
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* also be a caching one). We short circuit if the
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* buffer is locked (under I/O) and if it's in the
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* uptodate cache. The re-check from #2 catches the
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* case that the previous read-ahead completes just
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* before our is-it-in-flight check.
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*/
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if (flags & OCFS2_BH_CACHED &&
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!ocfs2_buffer_uptodate(inode, bh)) {
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mlog(ML_UPTODATE,
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"bh (%llu), inode %llu not uptodate\n",
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(unsigned long long)bh->b_blocknr,
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(unsigned long long)OCFS2_I(inode)->ip_blkno);
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ignore_cache = 1;
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}
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/* XXX: Can we ever get this and *not* have the cached
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* flag set? */
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if (buffer_jbd(bh)) {
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if (!(flags & OCFS2_BH_CACHED) || ignore_cache)
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mlog(ML_BH_IO, "trying to sync read a jbd "
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"managed bh (blocknr = %llu)\n",
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(unsigned long long)bh->b_blocknr);
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continue;
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}
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if (!(flags & OCFS2_BH_CACHED) || ignore_cache) {
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if (buffer_dirty(bh)) {
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/* This should probably be a BUG, or
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* at least return an error. */
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mlog(ML_BH_IO, "asking me to sync read a dirty "
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"buffer! (blocknr = %llu)\n",
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(unsigned long long)bh->b_blocknr);
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continue;
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}
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/* A read-ahead request was made - if the
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* buffer is already under read-ahead from a
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* previously submitted request than we are
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* done here. */
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if ((flags & OCFS2_BH_READAHEAD)
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&& ocfs2_buffer_read_ahead(inode, bh))
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continue;
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lock_buffer(bh);
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if (buffer_jbd(bh)) {
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#ifdef CATCH_BH_JBD_RACES
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mlog(ML_ERROR, "block %llu had the JBD bit set "
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"while I was in lock_buffer!",
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(unsigned long long)bh->b_blocknr);
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BUG();
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#else
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unlock_buffer(bh);
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continue;
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#endif
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}
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/* Re-check ocfs2_buffer_uptodate() as a
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* previously read-ahead buffer may have
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* completed I/O while we were waiting for the
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* buffer lock. */
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if ((flags & OCFS2_BH_CACHED)
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&& !(flags & OCFS2_BH_READAHEAD)
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&& ocfs2_buffer_uptodate(inode, bh)) {
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unlock_buffer(bh);
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continue;
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}
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clear_buffer_uptodate(bh);
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get_bh(bh); /* for end_buffer_read_sync() */
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bh->b_end_io = end_buffer_read_sync;
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submit_bh(READ, bh);
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continue;
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}
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}
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status = 0;
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for (i = (nr - 1); i >= 0; i--) {
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bh = bhs[i];
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if (!(flags & OCFS2_BH_READAHEAD)) {
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/* We know this can't have changed as we hold the
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* inode sem. Avoid doing any work on the bh if the
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* journal has it. */
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if (!buffer_jbd(bh))
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wait_on_buffer(bh);
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if (!buffer_uptodate(bh)) {
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/* Status won't be cleared from here on out,
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* so we can safely record this and loop back
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* to cleanup the other buffers. Don't need to
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* remove the clustered uptodate information
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* for this bh as it's not marked locally
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* uptodate. */
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status = -EIO;
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put_bh(bh);
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bhs[i] = NULL;
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continue;
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}
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}
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/* Always set the buffer in the cache, even if it was
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* a forced read, or read-ahead which hasn't yet
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* completed. */
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if (inode)
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ocfs2_set_buffer_uptodate(inode, bh);
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}
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if (inode)
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mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
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mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
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(unsigned long long)block, nr,
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(!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags);
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bail:
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mlog_exit(status);
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return status;
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}
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/* Check whether the blkno is the super block or one of the backups. */
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static void ocfs2_check_super_or_backup(struct super_block *sb,
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sector_t blkno)
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{
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int i;
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u64 backup_blkno;
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if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
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return;
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for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
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backup_blkno = ocfs2_backup_super_blkno(sb, i);
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if (backup_blkno == blkno)
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return;
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}
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BUG();
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}
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/*
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* Write super block and backups doesn't need to collaborate with journal,
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* so we don't need to lock ip_io_mutex and inode doesn't need to bea passed
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* into this function.
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*/
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int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
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struct buffer_head *bh)
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{
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int ret = 0;
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mlog_entry_void();
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BUG_ON(buffer_jbd(bh));
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ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
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if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
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ret = -EROFS;
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goto out;
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}
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lock_buffer(bh);
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set_buffer_uptodate(bh);
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/* remove from dirty list before I/O. */
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clear_buffer_dirty(bh);
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get_bh(bh); /* for end_buffer_write_sync() */
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bh->b_end_io = end_buffer_write_sync;
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submit_bh(WRITE, bh);
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wait_on_buffer(bh);
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if (!buffer_uptodate(bh)) {
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ret = -EIO;
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put_bh(bh);
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}
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out:
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mlog_exit(ret);
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return ret;
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}
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