[deliverable/linux.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/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"
#include "ocfs2_trace.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;

	trace_ocfs2_write_block((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;
		mlog_errno(ret);
		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;
		mlog_errno(ret);
	}

	ocfs2_metadata_cache_io_unlock(ci);
out:
	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;

	trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);

	if (!nr)
		goto bail;

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

		if (buffer_jbd(bh)) {
			trace_ocfs2_read_blocks_sync_jbd(
					(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)) {
#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
		}

		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);

	trace_ocfs2_read_blocks_begin(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) {
		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 = -ENOMEM;
				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)) {
			trace_ocfs2_read_blocks_from_disk(
			     (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;
		}

		trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
			ignore_cache, buffer_jbd(bh), buffer_dirty(bh));

		if (buffer_jbd(bh)) {
			continue;
		}

		if (ignore_cache) {
			if (buffer_dirty(bh)) {
				/* This should probably be a BUG, or
				 * at least return an error. */
				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)) {
			if (status) {
				/* Clear the rest of the buffers on error */
				put_bh(bh);
				bhs[i] = NULL;
				continue;
			}
			/* 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);

	trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
				    flags, ignore_cache);

bail:

	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;
	struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;

	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;
		mlog_errno(ret);
		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;
	ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
	submit_bh(WRITE, bh);

	wait_on_buffer(bh);

	if (!buffer_uptodate(bh)) {
		ret = -EIO;
		mlog_errno(ret);
	}

out:
	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>
ccd979bd MF	28	#include <linux/highmem.h>
	29
	30	#include <cluster/masklog.h>
	31
	32	#include "ocfs2.h"
	33
	34	#include "alloc.h"
	35	#include "inode.h"
	36	#include "journal.h"
	37	#include "uptodate.h"
ccd979bd	38	#include "buffer_head_io.h"
15057e98	39	#include "ocfs2_trace.h"
ccd979bd	40
970e4936 JB	41	/*
	42	* Bits on bh->b_state used by ocfs2.
	43	*
b86c86fa	44	* These MUST be after the JBD2 bits. Hence, we use BH_JBDPrivateStart.
970e4936 JB	45	*/
970e4936 JB	46	enum ocfs2_state_bits {
b86c86fa	47	BH_NeedsValidate = BH_JBDPrivateStart,
970e4936 JB	48	};
	49
	50	/* Expand the magic b_state functions */
	51	BUFFER_FNS(NeedsValidate, needs_validate);
	52
ccd979bd	53	int ocfs2_write_block(struct ocfs2_super osb, struct buffer_head bh,
8cb471e8	54	struct ocfs2_caching_info *ci)
ccd979bd MF	55	{
	56	int ret = 0;
	57
15057e98	58	trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci);
ccd979bd MF	59
	60	BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
	61	BUG_ON(buffer_jbd(bh));
	62
	63	/* No need to check for a soft readonly file system here. non
	64	* journalled writes are only ever done on system files which
	65	* can get modified during recovery even if read-only. */
	66	if (ocfs2_is_hard_readonly(osb)) {
	67	ret = -EROFS;
c1e8d35e	68	mlog_errno(ret);
ccd979bd MF	69	goto out;
	70	}
	71
8cb471e8	72	ocfs2_metadata_cache_io_lock(ci);
ccd979bd MF	73
	74	lock_buffer(bh);
	75	set_buffer_uptodate(bh);
	76
	77	/* remove from dirty list before I/O. */
	78	clear_buffer_dirty(bh);
	79
da1e9098	80	get_bh(bh); /* for end_buffer_write_sync() */
ccd979bd MF	81	bh->b_end_io = end_buffer_write_sync;
	82	submit_bh(WRITE, bh);
	83
	84	wait_on_buffer(bh);
	85
	86	if (buffer_uptodate(bh)) {
8cb471e8	87	ocfs2_set_buffer_uptodate(ci, bh);
ccd979bd MF	88	} else {
	89	/* We don't need to remove the clustered uptodate
	90	* information for this bh as it's not marked locally
	91	* uptodate. */
	92	ret = -EIO;
c1e8d35e	93	mlog_errno(ret);
ccd979bd MF	94	}
ccd979bd MF	95
8cb471e8	96	ocfs2_metadata_cache_io_unlock(ci);
ccd979bd	97	out:
ccd979bd MF	98	return ret;
	99	}
	100
da1e9098 JB	101	int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
	102	unsigned int nr, struct buffer_head *bhs[])
	103	{
	104	int status = 0;
	105	unsigned int i;
	106	struct buffer_head *bh;
	107
15057e98 TM	108	trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
	109
	110	if (!nr)
da1e9098	111	goto bail;
da1e9098 JB	112
	113	for (i = 0 ; i < nr ; i++) {
	114	if (bhs[i] == NULL) {
	115	bhs[i] = sb_getblk(osb->sb, block++);
	116	if (bhs[i] == NULL) {
7391a294	117	status = -ENOMEM;
da1e9098 JB	118	mlog_errno(status);
	119	goto bail;
	120	}
	121	}
	122	bh = bhs[i];
	123
	124	if (buffer_jbd(bh)) {
15057e98 TM	125	trace_ocfs2_read_blocks_sync_jbd(
15057e98 TM	126	(unsigned long long)bh->b_blocknr);
da1e9098 JB	127	continue;
	128	}
	129
	130	if (buffer_dirty(bh)) {
	131	/* This should probably be a BUG, or
	132	* at least return an error. */
	133	mlog(ML_ERROR,
	134	"trying to sync read a dirty "
	135	"buffer! (blocknr = %llu), skipping\n",
	136	(unsigned long long)bh->b_blocknr);
	137	continue;
	138	}
	139
	140	lock_buffer(bh);
	141	if (buffer_jbd(bh)) {
7186ee06	142	#ifdef CATCH_BH_JBD_RACES
da1e9098 JB	143	mlog(ML_ERROR,
	144	"block %llu had the JBD bit set "
	145	"while I was in lock_buffer!",
	146	(unsigned long long)bh->b_blocknr);
	147	BUG();
7186ee06 GH	148	#else
	149	unlock_buffer(bh);
	150	continue;
	151	#endif
da1e9098 JB	152	}
	153
	154	clear_buffer_uptodate(bh);
	155	get_bh(bh); /* for end_buffer_read_sync() */
	156	bh->b_end_io = end_buffer_read_sync;
	157	submit_bh(READ, bh);
	158	}
	159
	160	for (i = nr; i > 0; i--) {
	161	bh = bhs[i - 1];
	162
d6b58f89 MF	163	/* No need to wait on the buffer if it's managed by JBD. */
	164	if (!buffer_jbd(bh))
	165	wait_on_buffer(bh);
da1e9098	166
da1e9098 JB	167	if (!buffer_uptodate(bh)) {
	168	/* Status won't be cleared from here on out,
	169	* so we can safely record this and loop back
	170	* to cleanup the other buffers. */
	171	status = -EIO;
	172	put_bh(bh);
	173	bhs[i - 1] = NULL;
	174	}
	175	}
	176
	177	bail:
	178	return status;
	179	}
	180
8cb471e8	181	int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
970e4936 JB	182	struct buffer_head *bhs[], int flags,
	183	int (validate)(struct super_block sb,
	184	struct buffer_head *bh))
ccd979bd MF	185	{
ccd979bd MF	186	int status = 0;
ccd979bd MF	187	int i, ignore_cache = 0;
ccd979bd MF	188	struct buffer_head *bh;
8cb471e8	189	struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
ccd979bd	190
15057e98	191	trace_ocfs2_read_blocks_begin(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) {
ccd979bd MF	211	status = 0;
	212	goto bail;
	213	}
	214
8cb471e8	215	ocfs2_metadata_cache_io_lock(ci);
ccd979bd MF	216	for (i = 0 ; i < nr ; i++) {
ccd979bd MF	217	if (bhs[i] == NULL) {
8cb471e8	218	bhs[i] = sb_getblk(sb, block++);
ccd979bd	219	if (bhs[i] == NULL) {
8cb471e8	220	ocfs2_metadata_cache_io_unlock(ci);
7391a294	221	status = -ENOMEM;
ccd979bd MF	222	mlog_errno(status);
	223	goto bail;
	224	}
	225	}
	226	bh = bhs[i];
d4a8c93c	227	ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
ccd979bd	228
aa958874 MF	229	/* There are three read-ahead cases here which we need to
	230	* be concerned with. All three assume a buffer has
	231	* previously been submitted with OCFS2_BH_READAHEAD
	232	* and it hasn't yet completed I/O.
	233	*
	234	* 1) The current request is sync to disk. This rarely
	235	* happens these days, and never when performance
	236	* matters - the code can just wait on the buffer
	237	* lock and re-submit.
	238	*
	239	* 2) The current request is cached, but not
	240	* readahead. ocfs2_buffer_uptodate() will return
	241	* false anyway, so we'll wind up waiting on the
	242	* buffer lock to do I/O. We re-check the request
	243	* with after getting the lock to avoid a re-submit.
	244	*
	245	* 3) The current request is readahead (and so must
	246	* also be a caching one). We short circuit if the
	247	* buffer is locked (under I/O) and if it's in the
	248	* uptodate cache. The re-check from #2 catches the
	249	* case that the previous read-ahead completes just
	250	* before our is-it-in-flight check.
	251	*/
	252
8cb471e8	253	if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
d701485a	254	trace_ocfs2_read_blocks_from_disk(
ccd979bd	255	(unsigned long long)bh->b_blocknr,
8cb471e8	256	(unsigned long long)ocfs2_metadata_cache_owner(ci));
d4a8c93c JB	257	/* We're using ignore_cache here to say
d4a8c93c JB	258	* "go to disk" */
ccd979bd MF	259	ignore_cache = 1;
	260	}
	261
15057e98 TM	262	trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
	263	ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
	264
ccd979bd	265	if (buffer_jbd(bh)) {
ccd979bd MF	266	continue;
	267	}
	268
d4a8c93c	269	if (ignore_cache) {
ccd979bd MF	270	if (buffer_dirty(bh)) {
	271	/* This should probably be a BUG, or
	272	* at least return an error. */
ccd979bd MF	273	continue;
	274	}
	275
aa958874 MF	276	/* A read-ahead request was made - if the
	277	* buffer is already under read-ahead from a
	278	* previously submitted request than we are
	279	* done here. */
	280	if ((flags & OCFS2_BH_READAHEAD)
8cb471e8	281	&& ocfs2_buffer_read_ahead(ci, bh))
aa958874 MF	282	continue;
aa958874 MF	283
ccd979bd MF	284	lock_buffer(bh);
	285	if (buffer_jbd(bh)) {
	286	#ifdef CATCH_BH_JBD_RACES
	287	mlog(ML_ERROR, "block %llu had the JBD bit set "
	288	"while I was in lock_buffer!",
	289	(unsigned long long)bh->b_blocknr);
	290	BUG();
	291	#else
	292	unlock_buffer(bh);
	293	continue;
	294	#endif
	295	}
aa958874 MF	296
	297	/* Re-check ocfs2_buffer_uptodate() as a
	298	* previously read-ahead buffer may have
	299	* completed I/O while we were waiting for the
	300	* buffer lock. */
d4a8c93c	301	if (!(flags & OCFS2_BH_IGNORE_CACHE)
aa958874	302	&& !(flags & OCFS2_BH_READAHEAD)
8cb471e8	303	&& ocfs2_buffer_uptodate(ci, bh)) {
aa958874 MF	304	unlock_buffer(bh);
	305	continue;
	306	}
	307
ccd979bd MF	308	clear_buffer_uptodate(bh);
ccd979bd MF	309	get_bh(bh); /* for end_buffer_read_sync() */
970e4936 JB	310	if (validate)
970e4936 JB	311	set_buffer_needs_validate(bh);
ccd979bd	312	bh->b_end_io = end_buffer_read_sync;
aa958874	313	submit_bh(READ, bh);
ccd979bd MF	314	continue;
	315	}
	316	}
	317
	318	status = 0;
	319
	320	for (i = (nr - 1); i >= 0; i--) {
	321	bh = bhs[i];
	322
aa958874	323	if (!(flags & OCFS2_BH_READAHEAD)) {
34237681 GR	324	if (status) {
	325	/* Clear the rest of the buffers on error */
	326	put_bh(bh);
	327	bhs[i] = NULL;
	328	continue;
	329	}
aa958874	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
15057e98 TM	371	trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
15057e98 TM	372	flags, ignore_cache);
ccd979bd MF	373
	374	bail:
	375
ccd979bd MF	376	return status;
ccd979bd MF	377	}
d659072f TM	378
	379	/* Check whether the blkno is the super block or one of the backups. */
	380	static void ocfs2_check_super_or_backup(struct super_block *sb,
	381	sector_t blkno)
	382	{
	383	int i;
	384	u64 backup_blkno;
	385
	386	if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
	387	return;
	388
	389	for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
	390	backup_blkno = ocfs2_backup_super_blkno(sb, i);
	391	if (backup_blkno == blkno)
	392	return;
	393	}
	394
	395	BUG();
	396	}
	397
	398	/*
	399	* Write super block and backups doesn't need to collaborate with journal,
8cb471e8	400	* so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
d659072f TM	401	* into this function.
	402	*/
	403	int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
	404	struct buffer_head *bh)
	405	{
	406	int ret = 0;
a42ab8e1	407	struct ocfs2_dinode di = (struct ocfs2_dinode )bh->b_data;
d659072f	408
d659072f TM	409	BUG_ON(buffer_jbd(bh));
	410	ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
	411
	412	if (ocfs2_is_hard_readonly(osb) \|\| ocfs2_is_soft_readonly(osb)) {
	413	ret = -EROFS;
c1e8d35e	414	mlog_errno(ret);
d659072f TM	415	goto out;
	416	}
	417
	418	lock_buffer(bh);
	419	set_buffer_uptodate(bh);
	420
	421	/* remove from dirty list before I/O. */
	422	clear_buffer_dirty(bh);
	423
	424	get_bh(bh); /* for end_buffer_write_sync() */
	425	bh->b_end_io = end_buffer_write_sync;
a42ab8e1	426	ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
d659072f TM	427	submit_bh(WRITE, bh);
	428
	429	wait_on_buffer(bh);
	430
	431	if (!buffer_uptodate(bh)) {
	432	ret = -EIO;
c1e8d35e	433	mlog_errno(ret);
d659072f TM	434	}
	435
	436	out:
d659072f TM	437	return ret;
d659072f TM	438	}