When a series of O_DIRECT reads or writes are truncated, either due to
eof or due to an error, then we should return the number of contiguous
bytes that were received/sent starting at the offset specified by the
application.
Currently, we are failing to correctly check contiguity, and so we're
failing the generic/465 in xfstests when the race between the read
and write RPCs causes the file to get extended while the 2 reads are
outstanding. If the first read RPC call wins the race and returns with
eof set, we should treat the second read RPC as being truncated.
Reported-by: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
Fixes: 1ccbad9f9f9bd ("nfs: fix DIO good bytes calculation")
Cc: stable@xxxxxxxxxxxxxxx # 4.1+
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/nfs/direct.c | 78 +++++++++++++++++++++++++++----------------------
1 file changed, 43 insertions(+), 35 deletions(-)
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 222d7115db71..98a9a0bcdf38 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -123,32 +123,49 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
}
static void
-nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
+nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
+ const struct nfs_pgio_header *hdr,
+ ssize_t dreq_len)
{
- int i;
- ssize_t count;
+ struct nfs_direct_mirror *mirror = &dreq->mirrors[hdr->pgio_mirror_idx];
+
+ if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
+ test_bit(NFS_IOHDR_EOF, &hdr->flags)))
+ return;
+ if (dreq->max_count >= dreq_len) {
+ dreq->max_count = dreq_len;
+ if (dreq->count > dreq_len)
+ dreq->count = dreq_len;
+
+ if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
+ dreq->error = hdr->error;
+ else /* Clear outstanding error if this is EOF */
+ dreq->error = 0;
+ }
+ if (mirror->count > dreq_len)
+ mirror->count = dreq_len;
+}
- WARN_ON_ONCE(dreq->count >= dreq->max_count);
+static void
+nfs_direct_count_bytes(struct nfs_direct_req *dreq,
+ const struct nfs_pgio_header *hdr)
+{
+ struct nfs_direct_mirror *mirror = &dreq->mirrors[hdr->pgio_mirror_idx];
+ loff_t hdr_end = hdr->io_start + hdr->good_bytes;
+ ssize_t dreq_len = 0;
- if (dreq->mirror_count == 1) {
- dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes;
- dreq->count += hdr->good_bytes;
- } else {
- /* mirrored writes */
- count = dreq->mirrors[hdr->pgio_mirror_idx].count;
- if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {
- count = hdr->io_start + hdr->good_bytes - dreq->io_start;
- dreq->mirrors[hdr->pgio_mirror_idx].count = count;
- }
- /* update the dreq->count by finding the minimum agreed count from all
- * mirrors */
- count = dreq->mirrors[0].count;
+ if (hdr_end > dreq->io_start)
+ dreq_len = hdr_end - dreq->io_start;
- for (i = 1; i < dreq->mirror_count; i++)
- count = min(count, dreq->mirrors[i].count);
+ nfs_direct_handle_truncated(dreq, hdr, dreq_len);
- dreq->count = count;
- }
+ if (dreq_len > dreq->max_count)
+ dreq_len = dreq->max_count;
+
+ if (mirror->count < dreq_len)
+ mirror->count = dreq_len;
+ if (dreq->count < dreq_len)
+ dreq->count = dreq_len;
}
/*
@@ -402,20 +419,12 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
struct nfs_direct_req *dreq = hdr->dreq;
spin_lock(&dreq->lock);
- if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
- dreq->error = hdr->error;
-
if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
spin_unlock(&dreq->lock);
goto out_put;
}
- if (hdr->good_bytes != 0)
- nfs_direct_good_bytes(dreq, hdr);
-
- if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
- dreq->error = 0;
-
+ nfs_direct_count_bytes(dreq, hdr);
spin_unlock(&dreq->lock);
while (!list_empty(&hdr->pages)) {
@@ -652,6 +661,9 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
dreq->count = 0;
+ dreq->max_count = 0;
+ list_for_each_entry(req, &reqs, wb_list)
+ dreq->max_count += req->wb_bytes;
dreq->verf.committed = NFS_INVALID_STABLE_HOW;
nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
for (i = 0; i < dreq->mirror_count; i++)
@@ -791,17 +803,13 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
nfs_init_cinfo_from_dreq(&cinfo, dreq);
spin_lock(&dreq->lock);
-
- if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))
- dreq->error = hdr->error;
-
if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
spin_unlock(&dreq->lock);
goto out_put;
}
+ nfs_direct_count_bytes(dreq, hdr);
if (hdr->good_bytes != 0) {
- nfs_direct_good_bytes(dreq, hdr);
if (nfs_write_need_commit(hdr)) {
if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
request_commit = true;
--
2.21.0
