/* -*- mode: c; c-basic-offset: 8; -*- * vim: noexpandtab sw=8 ts=8 sts=0: * * io.c * * Buffer cache handling * * 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/types.h> #include <linux/slab.h> #include <linux/highmem.h> #include <cluster/masklog.h> #include "ocfs2.h" #include "alloc.h" #include "inode.h" #include "journal.h" #include "uptodate.h" #include "buffer_head_io.h" int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh, struct inode *inode) { int ret = 0; mlog_entry("(bh->b_blocknr = %llu, inode=%p)\n", (unsigned long long)bh->b_blocknr, inode); BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO); BUG_ON(buffer_jbd(bh)); /* No need to check for a soft readonly file system here. non * journalled writes are only ever done on system files which * can get modified during recovery even if read-only. */ if (ocfs2_is_hard_readonly(osb)) { ret = -EROFS; goto out; } mutex_lock(&OCFS2_I(inode)->ip_io_mutex); lock_buffer(bh); set_buffer_uptodate(bh); /* remove from dirty list before I/O. */ clear_buffer_dirty(bh); get_bh(bh); /* for end_buffer_write_sync() */ bh->b_end_io = end_buffer_write_sync; submit_bh(WRITE, bh); wait_on_buffer(bh); if (buffer_uptodate(bh)) { ocfs2_set_buffer_uptodate(inode, bh); } else { /* We don't need to remove the clustered uptodate * information for this bh as it's not marked locally * uptodate. */ ret = -EIO; brelse(bh); } mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); out: mlog_exit(ret); return ret; } int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, struct buffer_head *bhs[], int flags, struct inode *inode) { int status = 0; struct super_block *sb; int i, ignore_cache = 0; struct buffer_head *bh; mlog_entry("(block=(%llu), nr=(%d), flags=%d, inode=%p)\n", (unsigned long long)block, nr, flags, inode); BUG_ON((flags & OCFS2_BH_READAHEAD) && (!inode || !(flags & OCFS2_BH_CACHED))); if (osb == NULL || osb->sb == NULL || bhs == NULL) { status = -EINVAL; mlog_errno(status); goto bail; } if (nr < 0) { mlog(ML_ERROR, "asked to read %d blocks!\n", nr); status = -EINVAL; mlog_errno(status); goto bail; } if (nr == 0) { mlog(ML_BH_IO, "No buffers will be read!\n"); status = 0; goto bail; } sb = osb->sb; if (flags & OCFS2_BH_CACHED && !inode) flags &= ~OCFS2_BH_CACHED; if (inode) mutex_lock(&OCFS2_I(inode)->ip_io_mutex); for (i = 0 ; i < nr ; i++) { if (bhs[i] == NULL) { bhs[i] = sb_getblk(sb, block++); if (bhs[i] == NULL) { if (inode) mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); status = -EIO; mlog_errno(status); goto bail; } } bh = bhs[i]; ignore_cache = 0; /* There are three read-ahead cases here which we need to * be concerned with. All three assume a buffer has * previously been submitted with OCFS2_BH_READAHEAD * and it hasn't yet completed I/O. * * 1) The current request is sync to disk. This rarely * happens these days, and never when performance * matters - the code can just wait on the buffer * lock and re-submit. * * 2) The current request is cached, but not * readahead. ocfs2_buffer_uptodate() will return * false anyway, so we'll wind up waiting on the * buffer lock to do I/O. We re-check the request * with after getting the lock to avoid a re-submit. * * 3) The current request is readahead (and so must * also be a caching one). We short circuit if the * buffer is locked (under I/O) and if it's in the * uptodate cache. The re-check from #2 catches the * case that the previous read-ahead completes just * before our is-it-in-flight check. */ if (flags & OCFS2_BH_CACHED && !ocfs2_buffer_uptodate(inode, bh)) { mlog(ML_UPTODATE, "bh (%llu), inode %llu not uptodate\n", (unsigned long long)bh->b_blocknr, (unsigned long long)OCFS2_I(inode)->ip_blkno); ignore_cache = 1; } /* XXX: Can we ever get this and *not* have the cached * flag set? */ if (buffer_jbd(bh)) { if (!(flags & OCFS2_BH_CACHED) || ignore_cache) mlog(ML_BH_IO, "trying to sync read a jbd " "managed bh (blocknr = %llu)\n", (unsigned long long)bh->b_blocknr); continue; } if (!(flags & OCFS2_BH_CACHED) || ignore_cache) { if (buffer_dirty(bh)) { /* This should probably be a BUG, or * at least return an error. */ mlog(ML_BH_IO, "asking me to sync read a dirty " "buffer! (blocknr = %llu)\n", (unsigned long long)bh->b_blocknr); continue; } /* A read-ahead request was made - if the * buffer is already under read-ahead from a * previously submitted request than we are * done here. */ if ((flags & OCFS2_BH_READAHEAD) && ocfs2_buffer_read_ahead(inode, bh)) continue; lock_buffer(bh); if (buffer_jbd(bh)) { #ifdef CATCH_BH_JBD_RACES mlog(ML_ERROR, "block %llu had the JBD bit set " "while I was in lock_buffer!", (unsigned long long)bh->b_blocknr); BUG(); #else unlock_buffer(bh); continue; #endif } /* Re-check ocfs2_buffer_uptodate() as a * previously read-ahead buffer may have * completed I/O while we were waiting for the * buffer lock. */ if ((flags & OCFS2_BH_CACHED) && !(flags & OCFS2_BH_READAHEAD) && ocfs2_buffer_uptodate(inode, bh)) { unlock_buffer(bh); continue; } clear_buffer_uptodate(bh); get_bh(bh); /* for end_buffer_read_sync() */ bh->b_end_io = end_buffer_read_sync; submit_bh(READ, bh); continue; } } status = 0; for (i = (nr - 1); i >= 0; i--) { bh = bhs[i]; if (!(flags & OCFS2_BH_READAHEAD)) { /* We know this can't have changed as we hold the * inode sem. Avoid doing any work on the bh if the * journal has it. */ if (!buffer_jbd(bh)) wait_on_buffer(bh); if (!buffer_uptodate(bh)) { /* Status won't be cleared from here on out, * so we can safely record this and loop back * to cleanup the other buffers. Don't need to * remove the clustered uptodate information * for this bh as it's not marked locally * uptodate. */ status = -EIO; brelse(bh); bhs[i] = NULL; continue; } } /* Always set the buffer in the cache, even if it was * a forced read, or read-ahead which hasn't yet * completed. */ if (inode) ocfs2_set_buffer_uptodate(inode, bh); } if (inode) mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", (unsigned long long)block, nr, (!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags); bail: mlog_exit(status); return status; }