diff options
| author | David Howells | 2022-05-27 13:45:28 +0100 |
|---|---|---|
| committer | David Howells | 2023-12-28 09:45:19 +0000 |
| commit | 768ddb1eacf5dd997ecf393e7bab9796bad047e0 (patch) | |
| tree | 95eca7d52ed1166adc05c97b0ecf3862d3172a43 | |
| parent | cae932d3aee55035a54415dcea8e7ecf2ec469b5 (diff) | |
netfs: Limit subrequest by size or number of segments
Limit a subrequest to a maximum size and/or a maximum number of contiguous
physical regions. This permits, for instance, an subreq's iterator to be
limited to the number of DMA'able segments that a large RDMA request can
handle.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
| -rw-r--r-- | fs/netfs/io.c | 18 | ||||
| -rw-r--r-- | include/linux/netfs.h | 1 | ||||
| -rw-r--r-- | include/trace/events/netfs.h | 1 |
3 files changed, 20 insertions, 0 deletions
diff --git a/fs/netfs/io.c b/fs/netfs/io.c index e9d408e211b8..e228bfb530ea 100644 --- a/fs/netfs/io.c +++ b/fs/netfs/io.c @@ -525,6 +525,7 @@ netfs_rreq_prepare_read(struct netfs_io_request *rreq, struct iov_iter *io_iter) { enum netfs_io_source source; + size_t lsize; _enter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size); @@ -547,13 +548,30 @@ netfs_rreq_prepare_read(struct netfs_io_request *rreq, source = NETFS_INVALID_READ; goto out; } + + if (subreq->max_nr_segs) { + lsize = netfs_limit_iter(io_iter, 0, subreq->len, + subreq->max_nr_segs); + if (subreq->len > lsize) { + subreq->len = lsize; + trace_netfs_sreq(subreq, netfs_sreq_trace_limited); + } + } } + if (subreq->len > rreq->len) + pr_warn("R=%08x[%u] SREQ>RREQ %zx > %zx\n", + rreq->debug_id, subreq->debug_index, + subreq->len, rreq->len); + if (WARN_ON(subreq->len == 0)) { source = NETFS_INVALID_READ; goto out; } + subreq->source = source; + trace_netfs_sreq(subreq, netfs_sreq_trace_prepare); + subreq->io_iter = *io_iter; iov_iter_truncate(&subreq->io_iter, subreq->len); iov_iter_advance(io_iter, subreq->len); diff --git a/include/linux/netfs.h b/include/linux/netfs.h index d673d0785b9d..44cd13ad695a 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -161,6 +161,7 @@ struct netfs_io_subrequest { refcount_t ref; short error; /* 0 or error that occurred */ unsigned short debug_index; /* Index in list (for debugging output) */ + unsigned int max_nr_segs; /* 0 or max number of segments in an iterator */ enum netfs_io_source source; /* Where to read from/write to */ unsigned long flags; #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */ diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h index beec534cbaab..fce6d0bc78e5 100644 --- a/include/trace/events/netfs.h +++ b/include/trace/events/netfs.h @@ -44,6 +44,7 @@ #define netfs_sreq_traces \ EM(netfs_sreq_trace_download_instead, "RDOWN") \ EM(netfs_sreq_trace_free, "FREE ") \ + EM(netfs_sreq_trace_limited, "LIMIT") \ EM(netfs_sreq_trace_prepare, "PREP ") \ EM(netfs_sreq_trace_resubmit_short, "SHORT") \ EM(netfs_sreq_trace_submit, "SUBMT") \ |