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@xxxxxxxxxx> cc: Jeff Layton <jlayton@xxxxxxxxxx> cc: linux-cachefs@xxxxxxxxxx cc: linux-fsdevel@xxxxxxxxxxxxxxx cc: linux-mm@xxxxxxxxx --- fs/netfs/io.c | 18 ++++++++++++++++++ include/linux/netfs.h | 1 + include/trace/events/netfs.h | 1 + 3 files changed, 20 insertions(+) diff --git a/fs/netfs/io.c b/fs/netfs/io.c index d8e9cd6ce338..c80b8eed1209 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 cd673596b411..20ddd46fa0bc 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -163,6 +163,7 @@ 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") \ -- You received this message because you are subscribed to the Google Groups "linux-cachefs@xxxxxxxxxx" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-cachefs+unsubscribe@xxxxxxxxxx.