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ocfs2: Wrap virtual block reads in ocfs2_read_virt_blocks()

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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: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This commit is contained in:
Joel Becker 2008-11-13 14:49:20 -08:00 committed by Mark Fasheh
parent 970e4936d7
commit a8549fb5ab
2 changed files with 95 additions and 0 deletions
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71
fs/ocfs2/extent_map.c
View File

@ -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;
}

24
fs/ocfs2/extent_map.h
View File

@ -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 */