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NFS: Fix O_DIRECT accounting of number of bytes read/written

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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@cn.fujitsu.com>
Fixes: 1ccbad9f9f ("nfs: fix DIO good bytes calculation")
Cc: stable@vger.kernel.org # 4.1+
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Trond Myklebust 2019-09-30 14:02:56 -04:00 committed by Anna Schumaker
parent 33ea5aaa87
commit 031d73ed76
1 changed files with 44 additions and 36 deletions
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80
fs/nfs/direct.c
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@ -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];
WARN_ON_ONCE(dreq->count >= dreq->max_count);
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 (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;
for (i = 1; i < dreq->mirror_count; i++)
count = min(count, dreq->mirrors[i].count);
dreq->count = count;
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;
}
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 (hdr_end > dreq->io_start)
dreq_len = hdr_end - dreq->io_start;
nfs_direct_handle_truncated(dreq, hdr, dreq_len);
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;