Tao Ma
2008-Aug-29 01:19 UTC
[Ocfs2-devel] [PATCH] ocfs2: support empty xattr bucket in find.
In ocfs2_xattr_buckets_find, when we meet with an empty
bucket, just skip it and try to find another non-empty one.
Note:
We erase empty bucket now when we find it has no xattr in it.
And there are actually many to-dos left if we really want to
disable automatic removal of empty buckets(e.g. when we insert
a new xattr cluster in xattr tree, we have to find a suitable
start hash, and an empty bucket can't give us such information.
That also means that we have to enhance our xattr bucket extension
process and so on). So I am not sure whether this patch should
be committed alone or with the future disabling patches.
Mark, it is up to you. ;)
Signed-off-by: Tao Ma <tao.ma at oracle.com>
---
fs/ocfs2/xattr.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 105 insertions(+), 0 deletions(-)
diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 2bc53b1..782abce 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -2241,6 +2241,80 @@ static int ocfs2_find_xe_in_bucket(struct inode *inode,
}
/*
+ * Try to find a non-empty bucket between low_bucket and high_bucket.
+ *
+ * First try to find one bucket that isn't empty between bucket and
+ * high_bucket. If none, try to find one bucket that isn't empty between
+ * bucket and low_bucket. If all are empty, return the lowest bucket.
+ */
+static int ocfs2_find_not_emtpy_bucket(struct inode *inode,
+ struct buffer_head **bucket_bh,
+ int *bucket,
+ int low_bucket,
+ int high_bucket,
+ u64 p_blkno)
+{
+ int i, ret = 0;
+ int old_bucket = *bucket;
+ struct buffer_head *bh = NULL;
+ struct ocfs2_xattr_header *xh = NULL;
+ u16 blk_per_bucket = ocfs2_blocks_per_xattr_bucket(inode->i_sb);
+ u64 blkno;
+
+ for (i = old_bucket + 1; i <= high_bucket; i++) {
+ blkno = p_blkno + i * blk_per_bucket;
+
+ ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), blkno,
+ &bh, OCFS2_BH_CACHED, inode);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ xh = (struct ocfs2_xattr_header *)bh->b_data;
+
+ if (xh->xh_count)
+ goto find_out;
+
+ brelse(bh);
+ bh = NULL;
+ }
+
+ /*
+ * In case old_bucket is already the lowest one, and we
+ * haven't find one non-empty bucket above us, return it
+ * by starting iteration from itself.
+ */
+ i = old_bucket == low_bucket ? old_bucket : old_bucket - 1;
+ for (; i >= low_bucket; i--) {
+ brelse(bh);
+ bh = NULL;
+ blkno = p_blkno + i * blk_per_bucket;
+
+ ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), blkno,
+ &bh, OCFS2_BH_CACHED, inode);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ xh = (struct ocfs2_xattr_header *)bh->b_data;
+
+ if (xh->xh_count)
+ break;
+ }
+
+find_out:
+ *bucket_bh = bh;
+ *bucket = i;
+
+ mlog(0, "Find non-empty Bucket %llu.\n",
+ (unsigned long long)bh->b_blocknr);
+out:
+ return ret;
+}
+
+/*
* Find the specified xattr entry in a series of buckets.
* This series start from p_blkno and last for num_clusters.
* The ocfs2_xattr_header.xh_num_buckets of the first bucket contains
@@ -2294,6 +2368,37 @@ static int ocfs2_xattr_bucket_find(struct inode *inode,
}
xh = (struct ocfs2_xattr_header *)bh->b_data;
+
+ if (!xh->xh_count) {
+ mlog(0, "Bucket %llu is empty.\n",
+ (unsigned long long)bh->b_blocknr);
+ /*
+ * this bucket is empty.
+ * If we have comes to the end(low == high), just
+ * exit the loop.
+ *
+ * If not, try to find one bucket which isn't empty.
+ */
+ if (low_bucket == high_bucket)
+ break;
+
+ brelse(bh);
+ bh = NULL;
+ ret = ocfs2_find_not_emtpy_bucket(inode, &bh,
+ &bucket,
+ low_bucket,
+ high_bucket,
+ p_blkno);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ xh = (struct ocfs2_xattr_header *)bh->b_data;
+ if (!xh->xh_count)
+ break;
+ }
+
xe = &xh->xh_entries[0];
if (name_hash < le32_to_cpu(xe->xe_name_hash)) {
high_bucket = bucket - 1;
--
1.5.4.GIT