[linux-2.6-block.git] / fs / ocfs2 / buffer_head_io.c

/* -*- 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"

/*
 * Bits on bh->b_state used by ocfs2.
 *
 * These MUST be after the JBD2 bits.  Hence, we use BH_JBDPrivateStart.
 */
enum ocfs2_state_bits {
	BH_NeedsValidate = BH_JBDPrivateStart,
};

/* Expand the magic b_state functions */
BUFFER_FNS(NeedsValidate, needs_validate);

int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
		      struct ocfs2_caching_info *ci)
{
	int ret = 0;

	mlog_entry("(bh->b_blocknr = %llu, ci=%p)\n",
		   (unsigned long long)bh->b_blocknr, ci);

	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;
	}

	ocfs2_metadata_cache_io_lock(ci);

	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(ci, bh);
	} else {
		/* We don't need to remove the clustered uptodate
		 * information for this bh as it's not marked locally
		 * uptodate. */
		ret = -EIO;
		put_bh(bh);
	}

	ocfs2_metadata_cache_io_unlock(ci);
out:
	mlog_exit(ret);
	return ret;
}

int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
			   unsigned int nr, struct buffer_head *bhs[])
{
	int status = 0;
	unsigned int i;
	struct buffer_head *bh;

	if (!nr) {
		mlog(ML_BH_IO, "No buffers will be read!\n");
		goto bail;
	}

	for (i = 0 ; i < nr ; i++) {
		if (bhs[i] == NULL) {
			bhs[i] = sb_getblk(osb->sb, block++);
			if (bhs[i] == NULL) {
				status = -EIO;
				mlog_errno(status);
				goto bail;
			}
		}
		bh = bhs[i];

		if (buffer_jbd(bh)) {
			mlog(ML_BH_IO,
			     "trying to sync read a jbd "
			     "managed bh (blocknr = %llu), skipping\n",
			     (unsigned long long)bh->b_blocknr);
			continue;
		}

		if (buffer_dirty(bh)) {
			/* This should probably be a BUG, or
			 * at least return an error. */
			mlog(ML_ERROR,
			     "trying to sync read a dirty "
			     "buffer! (blocknr = %llu), skipping\n",
			     (unsigned long long)bh->b_blocknr);
			continue;
		}

		lock_buffer(bh);
		if (buffer_jbd(bh)) {
			mlog(ML_ERROR,
			     "block %llu had the JBD bit set "
			     "while I was in lock_buffer!",
			     (unsigned long long)bh->b_blocknr);
			BUG();
		}

		clear_buffer_uptodate(bh);
		get_bh(bh); /* for end_buffer_read_sync() */
		bh->b_end_io = end_buffer_read_sync;
		submit_bh(READ, bh);
	}

	for (i = nr; i > 0; i--) {
		bh = bhs[i - 1];

		/* No need to wait on the buffer if it's managed by JBD. */
		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. */
			status = -EIO;
			put_bh(bh);
			bhs[i - 1] = NULL;
		}
	}

bail:
	return status;
}

int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
		      struct buffer_head *bhs[], int flags,
		      int (*validate)(struct super_block *sb,
				      struct buffer_head *bh))
{
	int status = 0;
	int i, ignore_cache = 0;
	struct buffer_head *bh;
	struct super_block *sb = ocfs2_metadata_cache_get_super(ci);

	mlog_entry("(ci=%p, block=(%llu), nr=(%d), flags=%d)\n",
		   ci, (unsigned long long)block, nr, flags);

	BUG_ON(!ci);
	BUG_ON((flags & OCFS2_BH_READAHEAD) &&
	       (flags & OCFS2_BH_IGNORE_CACHE));

	if (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;
	}

	ocfs2_metadata_cache_io_lock(ci);
	for (i = 0 ; i < nr ; i++) {
		if (bhs[i] == NULL) {
			bhs[i] = sb_getblk(sb, block++);
			if (bhs[i] == NULL) {
				ocfs2_metadata_cache_io_unlock(ci);
				status = -EIO;
				mlog_errno(status);
				goto bail;
			}
		}
		bh = bhs[i];
		ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);

		/* 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 (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
			mlog(ML_UPTODATE,
			     "bh (%llu), owner %llu not uptodate\n",
			     (unsigned long long)bh->b_blocknr,
			     (unsigned long long)ocfs2_metadata_cache_owner(ci));
			/* We're using ignore_cache here to say
			 * "go to disk" */
			ignore_cache = 1;
		}

		if (buffer_jbd(bh)) {
			if (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 (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(ci, 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_IGNORE_CACHE)
			    && !(flags & OCFS2_BH_READAHEAD)
			    && ocfs2_buffer_uptodate(ci, bh)) {
				unlock_buffer(bh);
				continue;
			}

			clear_buffer_uptodate(bh);
			get_bh(bh); /* for end_buffer_read_sync() */
			if (validate)
				set_buffer_needs_validate(bh);
			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
			 * owner 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;
				put_bh(bh);
				bhs[i] = NULL;
				continue;
			}

			if (buffer_needs_validate(bh)) {
				/* We never set NeedsValidate if the
				 * buffer was held by the journal, so
				 * that better not have changed */
				BUG_ON(buffer_jbd(bh));
				clear_buffer_needs_validate(bh);
				status = validate(sb, bh);
				if (status) {
					put_bh(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. */
		ocfs2_set_buffer_uptodate(ci, bh);
	}
	ocfs2_metadata_cache_io_unlock(ci);

	mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", 
	     (unsigned long long)block, nr,
	     ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes",
	     flags);

bail:

	mlog_exit(status);
	return status;
}

/* Check whether the blkno is the super block or one of the backups. */
static void ocfs2_check_super_or_backup(struct super_block *sb,
					sector_t blkno)
{
	int i;
	u64 backup_blkno;

	if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
		return;

	for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
		backup_blkno = ocfs2_backup_super_blkno(sb, i);
		if (backup_blkno == blkno)
			return;
	}

	BUG();
}

/*
 * Write super block and backups doesn't need to collaborate with journal,
 * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
 * into this function.
 */
int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
				struct buffer_head *bh)
{
	int ret = 0;

	mlog_entry_void();

	BUG_ON(buffer_jbd(bh));
	ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);

	if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
		ret = -EROFS;
		goto out;
	}

	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)) {
		ret = -EIO;
		put_bh(bh);
	}

out:
	mlog_exit(ret);
	return ret;
}
Commit	Line	Data
ccd979bd MF	1	/* -- mode: c; c-basic-offset: 8; --
	2	* vim: noexpandtab sw=8 ts=8 sts=0:
	3	*
	4	* io.c
	5	*
	6	* Buffer cache handling
	7	*
	8	* Copyright (C) 2002, 2004 Oracle. All rights reserved.
	9	*
	10	* This program is free software; you can redistribute it and/or
	11	* modify it under the terms of the GNU General Public
	12	* License as published by the Free Software Foundation; either
	13	* version 2 of the License, or (at your option) any later version.
	14	*
	15	* This program is distributed in the hope that it will be useful,
	16	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	17	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	18	* General Public License for more details.
	19	*
	20	* You should have received a copy of the GNU General Public
	21	* License along with this program; if not, write to the
	22	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	23	* Boston, MA 021110-1307, USA.
	24	*/
	25
	26	#include <linux/fs.h>
	27	#include <linux/types.h>
	28	#include <linux/slab.h>
	29	#include <linux/highmem.h>
	30
	31	#include <cluster/masklog.h>
	32
	33	#include "ocfs2.h"
	34
	35	#include "alloc.h"
	36	#include "inode.h"
	37	#include "journal.h"
	38	#include "uptodate.h"
	39
	40	#include "buffer_head_io.h"
	41
970e4936 JB	42	/*
	43	* Bits on bh->b_state used by ocfs2.
	44	*
b86c86fa	45	* These MUST be after the JBD2 bits. Hence, we use BH_JBDPrivateStart.
970e4936 JB	46	*/
970e4936 JB	47	enum ocfs2_state_bits {
b86c86fa	48	BH_NeedsValidate = BH_JBDPrivateStart,
970e4936 JB	49	};
	50
	51	/* Expand the magic b_state functions */
	52	BUFFER_FNS(NeedsValidate, needs_validate);
	53
ccd979bd	54	int ocfs2_write_block(struct ocfs2_super osb, struct buffer_head bh,
8cb471e8	55	struct ocfs2_caching_info *ci)
ccd979bd MF	56	{
	57	int ret = 0;
	58
8cb471e8 JB	59	mlog_entry("(bh->b_blocknr = %llu, ci=%p)\n",
8cb471e8 JB	60	(unsigned long long)bh->b_blocknr, ci);
ccd979bd MF	61
	62	BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
	63	BUG_ON(buffer_jbd(bh));
	64
	65	/* No need to check for a soft readonly file system here. non
	66	* journalled writes are only ever done on system files which
	67	* can get modified during recovery even if read-only. */
	68	if (ocfs2_is_hard_readonly(osb)) {
	69	ret = -EROFS;
	70	goto out;
	71	}
	72
8cb471e8	73	ocfs2_metadata_cache_io_lock(ci);
ccd979bd MF	74
	75	lock_buffer(bh);
	76	set_buffer_uptodate(bh);
	77
	78	/* remove from dirty list before I/O. */
	79	clear_buffer_dirty(bh);
	80
da1e9098	81	get_bh(bh); /* for end_buffer_write_sync() */
ccd979bd MF	82	bh->b_end_io = end_buffer_write_sync;
	83	submit_bh(WRITE, bh);
	84
	85	wait_on_buffer(bh);
	86
	87	if (buffer_uptodate(bh)) {
8cb471e8	88	ocfs2_set_buffer_uptodate(ci, bh);
ccd979bd MF	89	} else {
	90	/* We don't need to remove the clustered uptodate
	91	* information for this bh as it's not marked locally
	92	* uptodate. */
	93	ret = -EIO;
2fe5c1d7	94	put_bh(bh);
ccd979bd MF	95	}
ccd979bd MF	96
8cb471e8	97	ocfs2_metadata_cache_io_unlock(ci);
ccd979bd MF	98	out:
	99	mlog_exit(ret);
	100	return ret;
	101	}
	102
da1e9098 JB	103	int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
	104	unsigned int nr, struct buffer_head *bhs[])
	105	{
	106	int status = 0;
	107	unsigned int i;
	108	struct buffer_head *bh;
	109
	110	if (!nr) {
	111	mlog(ML_BH_IO, "No buffers will be read!\n");
	112	goto bail;
	113	}
	114
	115	for (i = 0 ; i < nr ; i++) {
	116	if (bhs[i] == NULL) {
	117	bhs[i] = sb_getblk(osb->sb, block++);
	118	if (bhs[i] == NULL) {
	119	status = -EIO;
	120	mlog_errno(status);
	121	goto bail;
	122	}
	123	}
	124	bh = bhs[i];
	125
	126	if (buffer_jbd(bh)) {
d6b58f89	127	mlog(ML_BH_IO,
da1e9098 JB	128	"trying to sync read a jbd "
	129	"managed bh (blocknr = %llu), skipping\n",
	130	(unsigned long long)bh->b_blocknr);
	131	continue;
	132	}
	133
	134	if (buffer_dirty(bh)) {
	135	/* This should probably be a BUG, or
	136	* at least return an error. */
	137	mlog(ML_ERROR,
	138	"trying to sync read a dirty "
	139	"buffer! (blocknr = %llu), skipping\n",
	140	(unsigned long long)bh->b_blocknr);
	141	continue;
	142	}
	143
	144	lock_buffer(bh);
	145	if (buffer_jbd(bh)) {
	146	mlog(ML_ERROR,
	147	"block %llu had the JBD bit set "
	148	"while I was in lock_buffer!",
	149	(unsigned long long)bh->b_blocknr);
	150	BUG();
	151	}
	152
	153	clear_buffer_uptodate(bh);
	154	get_bh(bh); /* for end_buffer_read_sync() */
	155	bh->b_end_io = end_buffer_read_sync;
	156	submit_bh(READ, bh);
	157	}
	158
	159	for (i = nr; i > 0; i--) {
	160	bh = bhs[i - 1];
	161
d6b58f89 MF	162	/* No need to wait on the buffer if it's managed by JBD. */
	163	if (!buffer_jbd(bh))
	164	wait_on_buffer(bh);
da1e9098	165
da1e9098 JB	166	if (!buffer_uptodate(bh)) {
	167	/* Status won't be cleared from here on out,
	168	* so we can safely record this and loop back
	169	* to cleanup the other buffers. */
	170	status = -EIO;
	171	put_bh(bh);
	172	bhs[i - 1] = NULL;
	173	}
	174	}
	175
	176	bail:
	177	return status;
	178	}
	179
8cb471e8	180	int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
970e4936 JB	181	struct buffer_head *bhs[], int flags,
	182	int (validate)(struct super_block sb,
	183	struct buffer_head *bh))
ccd979bd MF	184	{
ccd979bd MF	185	int status = 0;
ccd979bd MF	186	int i, ignore_cache = 0;
ccd979bd MF	187	struct buffer_head *bh;
8cb471e8	188	struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
ccd979bd	189
8cb471e8 JB	190	mlog_entry("(ci=%p, block=(%llu), nr=(%d), flags=%d)\n",
8cb471e8 JB	191	ci, (unsigned long long)block, nr, flags);
ccd979bd	192
8cb471e8	193	BUG_ON(!ci);
d4a8c93c JB	194	BUG_ON((flags & OCFS2_BH_READAHEAD) &&
d4a8c93c JB	195	(flags & OCFS2_BH_IGNORE_CACHE));
aa958874	196
31d33073	197	if (bhs == NULL) {
ccd979bd MF	198	status = -EINVAL;
	199	mlog_errno(status);
	200	goto bail;
	201	}
	202
	203	if (nr < 0) {
	204	mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
	205	status = -EINVAL;
	206	mlog_errno(status);
	207	goto bail;
	208	}
	209
	210	if (nr == 0) {
	211	mlog(ML_BH_IO, "No buffers will be read!\n");
	212	status = 0;
	213	goto bail;
	214	}
	215
8cb471e8	216	ocfs2_metadata_cache_io_lock(ci);
ccd979bd MF	217	for (i = 0 ; i < nr ; i++) {
ccd979bd MF	218	if (bhs[i] == NULL) {
8cb471e8	219	bhs[i] = sb_getblk(sb, block++);
ccd979bd	220	if (bhs[i] == NULL) {
8cb471e8	221	ocfs2_metadata_cache_io_unlock(ci);
ccd979bd MF	222	status = -EIO;
	223	mlog_errno(status);
	224	goto bail;
	225	}
	226	}
	227	bh = bhs[i];
d4a8c93c	228	ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
ccd979bd	229
aa958874 MF	230	/* There are three read-ahead cases here which we need to
	231	* be concerned with. All three assume a buffer has
	232	* previously been submitted with OCFS2_BH_READAHEAD
	233	* and it hasn't yet completed I/O.
	234	*
	235	* 1) The current request is sync to disk. This rarely
	236	* happens these days, and never when performance
	237	* matters - the code can just wait on the buffer
	238	* lock and re-submit.
	239	*
	240	* 2) The current request is cached, but not
	241	* readahead. ocfs2_buffer_uptodate() will return
	242	* false anyway, so we'll wind up waiting on the
	243	* buffer lock to do I/O. We re-check the request
	244	* with after getting the lock to avoid a re-submit.
	245	*
	246	* 3) The current request is readahead (and so must
	247	* also be a caching one). We short circuit if the
	248	* buffer is locked (under I/O) and if it's in the
	249	* uptodate cache. The re-check from #2 catches the
	250	* case that the previous read-ahead completes just
	251	* before our is-it-in-flight check.
	252	*/
	253
8cb471e8	254	if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
ccd979bd	255	mlog(ML_UPTODATE,
8cb471e8	256	"bh (%llu), owner %llu not uptodate\n",
ccd979bd	257	(unsigned long long)bh->b_blocknr,
8cb471e8	258	(unsigned long long)ocfs2_metadata_cache_owner(ci));
d4a8c93c JB	259	/* We're using ignore_cache here to say
d4a8c93c JB	260	* "go to disk" */
ccd979bd MF	261	ignore_cache = 1;
	262	}
	263
ccd979bd	264	if (buffer_jbd(bh)) {
d4a8c93c	265	if (ignore_cache)
ccd979bd MF	266	mlog(ML_BH_IO, "trying to sync read a jbd "
	267	"managed bh (blocknr = %llu)\n",
	268	(unsigned long long)bh->b_blocknr);
	269	continue;
	270	}
	271
d4a8c93c	272	if (ignore_cache) {
ccd979bd MF	273	if (buffer_dirty(bh)) {
	274	/* This should probably be a BUG, or
	275	* at least return an error. */
	276	mlog(ML_BH_IO, "asking me to sync read a dirty "
	277	"buffer! (blocknr = %llu)\n",
	278	(unsigned long long)bh->b_blocknr);
	279	continue;
	280	}
	281
aa958874 MF	282	/* A read-ahead request was made - if the
	283	* buffer is already under read-ahead from a
	284	* previously submitted request than we are
	285	* done here. */
	286	if ((flags & OCFS2_BH_READAHEAD)
8cb471e8	287	&& ocfs2_buffer_read_ahead(ci, bh))
aa958874 MF	288	continue;
aa958874 MF	289
ccd979bd MF	290	lock_buffer(bh);
	291	if (buffer_jbd(bh)) {
	292	#ifdef CATCH_BH_JBD_RACES
	293	mlog(ML_ERROR, "block %llu had the JBD bit set "
	294	"while I was in lock_buffer!",
	295	(unsigned long long)bh->b_blocknr);
	296	BUG();
	297	#else
	298	unlock_buffer(bh);
	299	continue;
	300	#endif
	301	}
aa958874 MF	302
	303	/* Re-check ocfs2_buffer_uptodate() as a
	304	* previously read-ahead buffer may have
	305	* completed I/O while we were waiting for the
	306	* buffer lock. */
d4a8c93c	307	if (!(flags & OCFS2_BH_IGNORE_CACHE)
aa958874	308	&& !(flags & OCFS2_BH_READAHEAD)
8cb471e8	309	&& ocfs2_buffer_uptodate(ci, bh)) {
aa958874 MF	310	unlock_buffer(bh);
	311	continue;
	312	}
	313
ccd979bd MF	314	clear_buffer_uptodate(bh);
ccd979bd MF	315	get_bh(bh); /* for end_buffer_read_sync() */
970e4936 JB	316	if (validate)
970e4936 JB	317	set_buffer_needs_validate(bh);
ccd979bd	318	bh->b_end_io = end_buffer_read_sync;
aa958874	319	submit_bh(READ, bh);
ccd979bd MF	320	continue;
	321	}
	322	}
	323
	324	status = 0;
	325
	326	for (i = (nr - 1); i >= 0; i--) {
	327	bh = bhs[i];
	328
aa958874 MF	329	if (!(flags & OCFS2_BH_READAHEAD)) {
aa958874 MF	330	/* We know this can't have changed as we hold the
8cb471e8	331	* owner sem. Avoid doing any work on the bh if the
aa958874 MF	332	* journal has it. */
	333	if (!buffer_jbd(bh))
	334	wait_on_buffer(bh);
	335
	336	if (!buffer_uptodate(bh)) {
	337	/* Status won't be cleared from here on out,
	338	* so we can safely record this and loop back
	339	* to cleanup the other buffers. Don't need to
	340	* remove the clustered uptodate information
	341	* for this bh as it's not marked locally
	342	* uptodate. */
	343	status = -EIO;
2fe5c1d7	344	put_bh(bh);
aa958874 MF	345	bhs[i] = NULL;
	346	continue;
	347	}
970e4936 JB	348
	349	if (buffer_needs_validate(bh)) {
	350	/* We never set NeedsValidate if the
	351	* buffer was held by the journal, so
	352	* that better not have changed */
	353	BUG_ON(buffer_jbd(bh));
	354	clear_buffer_needs_validate(bh);
8cb471e8	355	status = validate(sb, bh);
970e4936 JB	356	if (status) {
	357	put_bh(bh);
	358	bhs[i] = NULL;
	359	continue;
	360	}
	361	}
ccd979bd MF	362	}
ccd979bd MF	363
aa958874 MF	364	/* Always set the buffer in the cache, even if it was
	365	* a forced read, or read-ahead which hasn't yet
	366	* completed. */
8cb471e8	367	ocfs2_set_buffer_uptodate(ci, bh);
ccd979bd	368	}
8cb471e8	369	ocfs2_metadata_cache_io_unlock(ci);
ccd979bd	370
aa958874	371	mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
b0697053	372	(unsigned long long)block, nr,
d4a8c93c JB	373	((flags & OCFS2_BH_IGNORE_CACHE) \|\| ignore_cache) ? "no" : "yes",
d4a8c93c JB	374	flags);
ccd979bd MF	375
	376	bail:
	377
	378	mlog_exit(status);
	379	return status;
	380	}
d659072f TM	381
	382	/* Check whether the blkno is the super block or one of the backups. */
	383	static void ocfs2_check_super_or_backup(struct super_block *sb,
	384	sector_t blkno)
	385	{
	386	int i;
	387	u64 backup_blkno;
	388
	389	if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
	390	return;
	391
	392	for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
	393	backup_blkno = ocfs2_backup_super_blkno(sb, i);
	394	if (backup_blkno == blkno)
	395	return;
	396	}
	397
	398	BUG();
	399	}
	400
	401	/*
	402	* Write super block and backups doesn't need to collaborate with journal,
8cb471e8	403	* so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
d659072f TM	404	* into this function.
	405	*/
	406	int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
	407	struct buffer_head *bh)
	408	{
	409	int ret = 0;
	410
	411	mlog_entry_void();
	412
	413	BUG_ON(buffer_jbd(bh));
	414	ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
	415
	416	if (ocfs2_is_hard_readonly(osb) \|\| ocfs2_is_soft_readonly(osb)) {
	417	ret = -EROFS;
	418	goto out;
	419	}
	420
	421	lock_buffer(bh);
	422	set_buffer_uptodate(bh);
	423
	424	/* remove from dirty list before I/O. */
	425	clear_buffer_dirty(bh);
	426
	427	get_bh(bh); /* for end_buffer_write_sync() */
	428	bh->b_end_io = end_buffer_write_sync;
	429	submit_bh(WRITE, bh);
	430
	431	wait_on_buffer(bh);
	432
	433	if (!buffer_uptodate(bh)) {
	434	ret = -EIO;
2fe5c1d7	435	put_bh(bh);
d659072f TM	436	}
	437
	438	out:
	439	mlog_exit(ret);
	440	return ret;
	441	}