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Commit a8549fb5 authored by Joel Becker's avatar Joel Becker Committed by Mark Fasheh
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ocfs2: Wrap virtual block reads in ocfs2_read_virt_blocks() 



The ocfs2_read_dir_block() function really maps an inode's virtual
blocks to physical ones before calling ocfs2_read_blocks().  Let's
extract that to common code, because other places might want to do that.

Other than the block number being virtual, ocfs2_read_virt_blocks()
takes the same arguments as ocfs2_read_blocks().  It converts those
virtual block numbers to physical before calling ocfs2_read_blocks()
directly.  If the blocks asked for are discontiguous, this can mean
multiple calls to ocfs2_read_blocks(), but this is mostly hidden from
the caller.

Like ocfs2_read_blocks(), the caller can pass in an existing
buffer_head.  This is usually done to pick up some readahead I/O.
ocfs2_read_virt_blocks() checks the buffer_head's block number
against the extent map - it must match.

Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
Signed-off-by: default avatarMark Fasheh <mfasheh@suse.com>
parent 970e4936

fs/ocfs2/extent_map.c

+71 −0
Original line number Diff line number Diff line
@@ -806,3 +806,74 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, 


	return ret;

}



int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,

			   struct buffer_head *bhs[], int flags,

			   int (*validate)(struct super_block *sb,

					   struct buffer_head *bh))

{

	int rc = 0;

	u64 p_block, p_count;

	int i, count, done = 0;



	mlog_entry("(inode = %p, v_block = %llu, nr = %d, bhs = %p, "

		   "flags = %x, validate = %p)\n",

		   inode, (unsigned long long)v_block, nr, bhs, flags,

		   validate);



	if (((v_block + nr - 1) << inode->i_sb->s_blocksize_bits) >=

	    i_size_read(inode)) {

		BUG_ON(!(flags & OCFS2_BH_READAHEAD));

		goto out;

	}



	while (done < nr) {

		down_read(&OCFS2_I(inode)->ip_alloc_sem);

		rc = ocfs2_extent_map_get_blocks(inode, v_block + done,

						 &p_block, &p_count, NULL);

		up_read(&OCFS2_I(inode)->ip_alloc_sem);

		if (rc) {

			mlog_errno(rc);

			break;

		}



		if (!p_block) {

			rc = -EIO;

			mlog(ML_ERROR,

			     "Inode #%llu contains a hole at offset %llu\n",

			     (unsigned long long)OCFS2_I(inode)->ip_blkno,

			     (unsigned long long)(v_block + done) <<

			     inode->i_sb->s_blocksize_bits);

			break;

		}



		count = nr - done;

		if (p_count < count)

			count = p_count;



		/*

		 * If the caller passed us bhs, they should have come

		 * from a previous readahead call to this function.  Thus,

		 * they should have the right b_blocknr.

		 */

		for (i = 0; i < count; i++) {

			if (!bhs[done + i])

				continue;

			BUG_ON(bhs[done + i]->b_blocknr != (p_block + i));

		}



		rc = ocfs2_read_blocks(inode, p_block, count, bhs + done,

				       flags, validate);

		if (rc) {

			mlog_errno(rc);

			break;

		}

		done += count;

	}



out:

	mlog_exit(rc);

	return rc;

}

fs/ocfs2/extent_map.h

+24 −0
Original line number Diff line number Diff line
@@ -57,4 +57,28 @@ int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster, 
			     u32 *p_cluster, u32 *num_clusters,

			     struct ocfs2_extent_list *el);



int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,

			   struct buffer_head *bhs[], int flags,

			   int (*validate)(struct super_block *sb,

					   struct buffer_head *bh));

static inline int ocfs2_read_virt_block(struct inode *inode, u64 v_block,

					struct buffer_head **bh,

					int (*validate)(struct super_block *sb,

							struct buffer_head *bh))

{

	int status = 0;



	if (bh == NULL) {

		printk("ocfs2: bh == NULL\n");

		status = -EINVAL;

		goto bail;

	}



	status = ocfs2_read_virt_blocks(inode, v_block, 1, bh, 0, validate);



bail:

	return status;

}





#endif  /* _EXTENT_MAP_H */