[Ocfs2-devel] [PATCH 4/4] ocfs2: do not use ocfs2_zero_extend during direct IO
Joseph Qi
joseph.qi at huawei.com
Wed Feb 25 01:35:05 PST 2015
In ocfs2_direct_IO_write, we use ocfs2_zero_extend to zero allocated
clusters in case of cluster not aligned. But ocfs2_zero_extend uses page
cache, this may happen that it clears the data which blockdev_direct_IO
has already witten.
We should use blkdev_issue_zeroout instead of ocfs2_zero_extend
during direct IO.
So fix this issue by introducing ocfs2_direct_IO_zero_extend and
ocfs2_direct_IO_extend_no_holes.
Reported-by: Yiwen Jiang <jiangyiwen at huawei.com>
Signed-off-by: Joseph Qi <joseph.qi at huawei.com>
Tested-by: Yiwen Jiang <jiangyiwen at huawei.com>
---
fs/ocfs2/aops.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 130 insertions(+), 8 deletions(-)
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 973a636..1b0463a 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -663,6 +663,117 @@ static int ocfs2_is_overwrite(struct ocfs2_super *osb,
return 0;
}
+static int ocfs2_direct_IO_zero_extend(struct ocfs2_super *osb,
+ struct inode *inode, loff_t offset,
+ u64 zero_len, int cluster_align)
+{
+ u32 p_cpos = 0;
+ u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, i_size_read(inode));
+ unsigned int num_clusters = 0;
+ unsigned int ext_flags = 0;
+ int ret = 0;
+
+ if (offset <= i_size_read(inode) || cluster_align)
+ return 0;
+
+ ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos, &num_clusters,
+ &ext_flags);
+ if (ret < 0) {
+ mlog_errno(ret);
+ return ret;
+ }
+
+ if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
+ u64 s = i_size_read(inode);
+ sector_t sector = (p_cpos << (osb->s_clustersize_bits - 9)) +
+ (do_div(s, osb->s_clustersize) >> 9);
+
+ ret = blkdev_issue_zeroout(osb->sb->s_bdev, sector,
+ zero_len >> 9, GFP_NOFS, false);
+ if (ret < 0)
+ mlog_errno(ret);
+ }
+
+ return ret;
+}
+
+static int ocfs2_direct_IO_extend_no_holes(struct ocfs2_super *osb,
+ struct inode *inode, loff_t offset)
+{
+ u64 zero_start, zero_len, total_zero_len;
+ u32 p_cpos = 0, clusters_to_add;
+ u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, i_size_read(inode));
+ unsigned int num_clusters = 0;
+ unsigned int ext_flags = 0;
+ u32 size_div, offset_div;
+ int ret = 0;
+
+ {
+ u64 o = offset;
+ u64 s = i_size_read(inode);
+
+ offset_div = do_div(o, osb->s_clustersize);
+ size_div = do_div(s, osb->s_clustersize);
+ }
+
+ if (offset <= i_size_read(inode))
+ return 0;
+
+ clusters_to_add = ocfs2_bytes_to_clusters(inode->i_sb, offset) -
+ ocfs2_bytes_to_clusters(inode->i_sb, i_size_read(inode));
+ total_zero_len = offset - i_size_read(inode);
+ if (clusters_to_add)
+ total_zero_len -= offset_div;
+
+ /* Allocate clusters to fill out holes, and this is only needed
+ * when we add more than one clusters. Otherwise the cluster will
+ * be allocated during direct IO */
+ if (clusters_to_add > 1) {
+ ret = ocfs2_extend_allocation(inode,
+ OCFS2_I(inode)->ip_clusters,
+ clusters_to_add - 1, 0);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+ }
+
+ while (total_zero_len) {
+ ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos, &num_clusters,
+ &ext_flags);
+ if (ret < 0) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ zero_start = ocfs2_clusters_to_bytes(osb->sb, p_cpos) +
+ size_div;
+ zero_len = ocfs2_clusters_to_bytes(osb->sb, num_clusters) -
+ size_div;
+ zero_len = min(total_zero_len, zero_len);
+
+ if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
+ ret = blkdev_issue_zeroout(osb->sb->s_bdev,
+ zero_start >> 9, zero_len >> 9,
+ GFP_NOFS, false);
+ if (ret < 0) {
+ mlog_errno(ret);
+ goto out;
+ }
+ }
+
+ total_zero_len -= zero_len;
+ v_cpos += ocfs2_bytes_to_clusters(osb->sb, zero_len + size_div);
+
+ /* Only at first iteration can be cluster not aligned.
+ * So set size_div to 0 for the rest */
+ size_div = 0;
+ }
+
+out:
+ return ret;
+}
+
static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
struct iov_iter *iter,
loff_t offset)
@@ -677,8 +788,8 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
struct buffer_head *di_bh = NULL;
size_t count = iter->count;
journal_t *journal = osb->journal->j_journal;
- u32 zero_len;
- int cluster_align;
+ u64 zero_len_head, zero_len_tail;
+ int cluster_align_head, cluster_align_tail;
loff_t final_size = offset + count;
int append_write = offset >= i_size_read(inode) ? 1 : 0;
unsigned int num_clusters = 0;
@@ -686,9 +797,16 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
{
u64 o = offset;
+ u64 s = i_size_read(inode);
+
+ zero_len_head = do_div(o, 1 << osb->s_clustersize_bits);
+ cluster_align_head = !zero_len_head;
- zero_len = do_div(o, 1 << osb->s_clustersize_bits);
- cluster_align = !zero_len;
+ zero_len_tail = osb->s_clustersize -
+ do_div(s, osb->s_clustersize);
+ if ((offset - i_size_read(inode)) < zero_len_tail)
+ zero_len_tail = offset - i_size_read(inode);
+ cluster_align_tail = !zero_len_tail;
}
/*
@@ -712,10 +830,13 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
goto clean_orphan;
}
+ /* zeroing out the previously allocated cluster tail
+ * that but not zeroed */
if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
- ret = ocfs2_zero_extend(inode, di_bh, offset);
+ ret = ocfs2_direct_IO_zero_extend(osb, inode, offset,
+ zero_len_tail, cluster_align_tail);
else
- ret = ocfs2_extend_no_holes(inode, di_bh, offset,
+ ret = ocfs2_direct_IO_extend_no_holes(osb, inode,
offset);
if (ret < 0) {
mlog_errno(ret);
@@ -768,7 +889,8 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
mlog_errno(ret);
}
} else if (written > 0 && append_write && !is_overwrite &&
- !cluster_align) {
+ !cluster_align_head) {
+ /* zeroing out the allocated cluster head */
u32 p_cpos = 0;
u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, offset);
@@ -790,7 +912,7 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
ret = blkdev_issue_zeroout(osb->sb->s_bdev,
p_cpos << (osb->s_clustersize_bits - 9),
- zero_len >> 9, GFP_NOFS, false);
+ zero_len_head >> 9, GFP_NOFS, false);
if (ret < 0)
mlog_errno(ret);
--
1.8.4.3
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