/* -*- 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
  ",
  			     (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);

  	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!
  ", 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)) {
  			/* 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;
  }