[PATCH 18/24] netfs: Speed up buffered reading

David Howells
2024-07-29T16:22:37Z

Improve the efficiency of buffered reads in a number of ways:

(1) Overhaul the algorithm in general so that it's a lot more compact and
split the read submission code between buffered and unbuffered
versions. The unbuffered version can be vastly simplified.

(2) Read-result collection is handed off to a work queue rather than being
done in the I/O thread. Multiple subrequests can be processes
simultaneously.

(3) When a subrequest is collected, any folios it fully spans are
collected and "spare" data on either side is donated to either the
previous or the next subrequest in the sequence.

Notes:

(*) Readahead expansion is massively slows down fio, presumably because it
causes a load of extra allocations, both folio and xarray, up front
before RPC requests can be transmitted.

(*) RDMA with cifs does appear to work, both with SIW and RXE.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
fs/9p/vfs_addr.c | 5 +-
fs/afs/file.c | 20 +-
fs/afs/fsclient.c | 9 +-
fs/afs/yfsclient.c | 9 +-
fs/ceph/addr.c | 72 ++--
fs/netfs/Makefile | 3 +-
fs/netfs/buffered_read.c | 677 ++++++++++++++++++++++++-----------
fs/netfs/direct_read.c | 147 +++++++-
fs/netfs/internal.h | 19 +-
fs/netfs/iterator.c | 50 +++
fs/netfs/main.c | 3 +-
fs/netfs/objects.c | 8 +-
fs/netfs/read_collect.c | 540 ++++++++++++++++++++++++++++
fs/netfs/read_retry.c | 256 +++++++++++++
fs/netfs/write_issue.c | 4 -
fs/nfs/fscache.c | 19 +-
fs/nfs/fscache.h | 7 +-
fs/smb/client/cifssmb.c | 6 +-
fs/smb/client/file.c | 57 +--
fs/smb/client/smb2pdu.c | 10 +-
include/linux/netfs.h | 24 +-
include/trace/events/netfs.h | 99 ++++-
22 files changed, 1707 insertions(+), 337 deletions(-)
create mode 100644 fs/netfs/read_collect.c
create mode 100644 fs/netfs/read_retry.c

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index a97ceb105cd8..ee2f24647303 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -77,7 +77,10 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
* cache won't be on server and is zeroes */
__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);

- netfs_subreq_terminated(subreq, err ?: total, false);
+ if (!err)
+ subreq->transferred += total;
+
+ netfs_read_subreq_terminated(subreq, err, false);
}

/**
diff --git a/fs/afs/file.c b/fs/afs/file.c
index addb106dba4c..492d857a3fa0 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -16,6 +16,7 @@
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/netfs.h>
+#include <trace/events/netfs.h>
#include "internal.h"

static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
@@ -242,8 +243,10 @@ static void afs_fetch_data_notify(struct afs_operation *op)

req->error = error;
if (subreq) {
- __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
- netfs_subreq_terminated(subreq, error ?: req->actual_len, false);
+ subreq->rreq->i_size = req->file_size;
+ if (req->pos + req->actual_len >= req->file_size)
+ __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
+ netfs_read_subreq_terminated(subreq, error, false);
req->subreq = NULL;
} else if (req->done) {
req->done(req);
@@ -261,6 +264,12 @@ static void afs_fetch_data_success(struct afs_operation *op)
afs_fetch_data_notify(op);
}

+static void afs_fetch_data_aborted(struct afs_operation *op)
+{
+ afs_check_for_remote_deletion(op);
+ afs_fetch_data_notify(op);
+}
+
static void afs_fetch_data_put(struct afs_operation *op)
{
op->fetch.req->error = afs_op_error(op);
@@ -271,7 +280,7 @@ static const struct afs_operation_ops afs_fetch_data_operation = {
.issue_afs_rpc = afs_fs_fetch_data,
.issue_yfs_rpc = yfs_fs_fetch_data,
.success = afs_fetch_data_success,
- .aborted = afs_check_for_remote_deletion,
+ .aborted = afs_fetch_data_aborted,
.failed = afs_fetch_data_notify,
.put = afs_fetch_data_put,
};
@@ -293,7 +302,7 @@ int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
op = afs_alloc_operation(req->key, vnode->volume);
if (IS_ERR(op)) {
if (req->subreq)
- netfs_subreq_terminated(req->subreq, PTR_ERR(op), false);
+ netfs_read_subreq_terminated(req->subreq, PTR_ERR(op), false);
return PTR_ERR(op);
}

@@ -312,7 +321,7 @@ static void afs_read_worker(struct work_struct *work)

fsreq = afs_alloc_read(GFP_NOFS);
if (!fsreq)
- return netfs_subreq_terminated(subreq, -ENOMEM, false);
+ return netfs_read_subreq_terminated(subreq, -ENOMEM, false);

fsreq->subreq = subreq;
fsreq->pos = subreq->start + subreq->transferred;
@@ -321,6 +330,7 @@ static void afs_read_worker(struct work_struct *work)
fsreq->vnode = vnode;
fsreq->iter = &subreq->io_iter;

+ trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
afs_fetch_data(fsreq->vnode, fsreq);
afs_put_read(fsreq);
}
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 79cd30775b7a..098fa034a1cc 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -304,6 +304,7 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
struct afs_vnode_param *vp = &op->file[0];
struct afs_read *req = op->fetch.req;
const __be32 *bp;
+ size_t count_before;
int ret;

_enter("{%u,%zu,%zu/%llu}",
@@ -345,10 +346,14 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)

/* extract the returned data */
case 2:
- _debug("extract data %zu/%llu",
- iov_iter_count(call->iter), req->actual_len);
+ count_before = call->iov_len;
+ _debug("extract data %zu/%llu", count_before, req->actual_len);

ret = afs_extract_data(call, true);
+ if (req->subreq) {
+ req->subreq->transferred += count_before - call->iov_len;
+ netfs_read_subreq_progress(req->subreq, false);
+ }
if (ret < 0)
return ret;

diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index f521e66d3bf6..024227aba4cd 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -355,6 +355,7 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
struct afs_vnode_param *vp = &op->file[0];
struct afs_read *req = op->fetch.req;
const __be32 *bp;
+ size_t count_before;
int ret;

_enter("{%u,%zu, %zu/%llu}",
@@ -391,10 +392,14 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)

/* extract the returned data */
case 2:
- _debug("extract data %zu/%llu",
- iov_iter_count(call->iter), req->actual_len);
+ count_before = call->iov_len;
+ _debug("extract data %zu/%llu", count_before, req->actual_len);

ret = afs_extract_data(call, true);
+ if (req->subreq) {
+ req->subreq->transferred += count_before - call->iov_len;
+ netfs_read_subreq_progress(req->subreq, false);
+ }
if (ret < 0)
return ret;

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 8c16bc5250ef..997843269304 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -205,21 +205,6 @@ static void ceph_netfs_expand_readahead(struct netfs_io_request *rreq)
}
}

-static bool ceph_netfs_clamp_length(struct netfs_io_subrequest *subreq)
-{
- struct inode *inode = subreq->rreq->inode;
- struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
- struct ceph_inode_info *ci = ceph_inode(inode);
- u64 objno, objoff;
- u32 xlen;
-
- /* Truncate the extent at the end of the current block */
- ceph_calc_file_object_mapping(&ci->i_layout, subreq->start, subreq->len,
- &objno, &objoff, &xlen);
- subreq->len = min(xlen, fsc->mount_options->rsize);
- return true;
-}
-
static void finish_netfs_read(struct ceph_osd_request *req)
{
struct inode *inode = req->r_inode;
@@ -263,7 +248,11 @@ static void finish_netfs_read(struct ceph_osd_request *req)
calc_pages_for(osd_data->alignment,
osd_data->length), false);
}
- netfs_subreq_terminated(subreq, err, false);
+ if (err > 0) {
+ subreq->transferred = err;
+ err = 0;
+ }
+ netfs_read_subreq_terminated(subreq, err, false);
iput(req->r_inode);
ceph_dec_osd_stopping_blocker(fsc->mdsc);
}
@@ -277,7 +266,6 @@ static bool ceph_netfs_issue_op_inline(struct netfs_io_subrequest *subreq)
struct ceph_mds_request *req;
struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
struct ceph_inode_info *ci = ceph_inode(inode);
- struct iov_iter iter;
ssize_t err = 0;
size_t len;
int mode;
@@ -312,17 +300,36 @@ static bool ceph_netfs_issue_op_inline(struct netfs_io_subrequest *subreq)
}

len = min_t(size_t, iinfo->inline_len - subreq->start, subreq->len);
- iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages, subreq->start, len);
- err = copy_to_iter(iinfo->inline_data + subreq->start, len, &iter);
- if (err == 0)
+ err = copy_to_iter(iinfo->inline_data + subreq->start, len, &subreq->io_iter);
+ if (err == 0) {
err = -EFAULT;
+ } else {
+ subreq->transferred += err;
+ err = 0;
+ }

ceph_mdsc_put_request(req);
out:
- netfs_subreq_terminated(subreq, err, false);
+ netfs_read_subreq_terminated(subreq, err, false);
return true;
}

+static int ceph_netfs_prepare_read(struct netfs_io_subrequest *subreq)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+ struct inode *inode = rreq->inode;
+ struct ceph_inode_info *ci = ceph_inode(inode);
+ struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
+ u64 objno, objoff;
+ u32 xlen;
+
+ /* Truncate the extent at the end of the current block */
+ ceph_calc_file_object_mapping(&ci->i_layout, subreq->start, subreq->len,
+ &objno, &objoff, &xlen);
+ rreq->io_streams[0].sreq_max_len = umin(xlen, fsc->mount_options->rsize);
+ return 0;
+}
+
static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *rreq = subreq->rreq;
@@ -332,9 +339,8 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
struct ceph_client *cl = fsc->client;
struct ceph_osd_request *req = NULL;
struct ceph_vino vino = ceph_vino(inode);
- struct iov_iter iter;
- int err = 0;
- u64 len = subreq->len;
+ int err;
+ u64 len;
bool sparse = IS_ENCRYPTED(inode) || ceph_test_mount_opt(fsc, SPARSEREAD);
u64 off = subreq->start;
int extent_cnt;
@@ -347,6 +353,12 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
if (ceph_has_inline_data(ci) && ceph_netfs_issue_op_inline(subreq))
return;

+ // TODO: This rounding here is slightly dodgy. It *should* work, for
+ // now, as the cache only deals in blocks that are a multiple of
+ // PAGE_SIZE and fscrypt blocks are at most PAGE_SIZE. What needs to
+ // happen is for the fscrypt driving to be moved into netfslib and the
+ // data in the cache also to be stored encrypted.
+ len = subreq->len;
ceph_fscrypt_adjust_off_and_len(inode, &off, &len);

req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout, vino,
@@ -369,8 +381,6 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
doutc(cl, "%llx.%llx pos=%llu orig_len=%zu len=%llu\n",
ceph_vinop(inode), subreq->start, subreq->len, len);

- iov_iter_xarray(&iter, ITER_DEST, &rreq->mapping->i_pages, subreq->start, len);
-
/*
* FIXME: For now, use CEPH_OSD_DATA_TYPE_PAGES instead of _ITER for
* encrypted inodes. We'd need infrastructure that handles an iov_iter
@@ -382,7 +392,7 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
struct page **pages;
size_t page_off;

- err = iov_iter_get_pages_alloc2(&iter, &pages, len, &page_off);
+ err = iov_iter_get_pages_alloc2(&subreq->io_iter, &pages, len, &page_off);
if (err < 0) {
doutc(cl, "%llx.%llx failed to allocate pages, %d\n",
ceph_vinop(inode), err);
@@ -397,7 +407,7 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0, false,
false);
} else {
- osd_req_op_extent_osd_iter(req, 0, &iter);
+ osd_req_op_extent_osd_iter(req, 0, &subreq->io_iter);
}
if (!ceph_inc_osd_stopping_blocker(fsc->mdsc)) {
err = -EIO;
@@ -412,13 +422,14 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
out:
ceph_osdc_put_request(req);
if (err)
- netfs_subreq_terminated(subreq, err, false);
+ netfs_read_subreq_terminated(subreq, err, false);
doutc(cl, "%llx.%llx result %d\n", ceph_vinop(inode), err);
}

static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
{
struct inode *inode = rreq->inode;
+ struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
struct ceph_client *cl = ceph_inode_to_client(inode);
int got = 0, want = CEPH_CAP_FILE_CACHE;
struct ceph_netfs_request_data *priv;
@@ -467,6 +478,7 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)

priv->caps = got;
rreq->netfs_priv = priv;
+ rreq->io_streams[0].sreq_max_len = fsc->mount_options->rsize;

out:
if (ret < 0)
@@ -491,9 +503,9 @@ static void ceph_netfs_free_request(struct netfs_io_request *rreq)
const struct netfs_request_ops ceph_netfs_ops = {
.init_request = ceph_init_request,
.free_request = ceph_netfs_free_request,
+ .prepare_read = ceph_netfs_prepare_read,
.issue_read = ceph_netfs_issue_read,
.expand_readahead = ceph_netfs_expand_readahead,
- .clamp_length = ceph_netfs_clamp_length,
.check_write_begin = ceph_netfs_check_write_begin,
};

diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
index 8e6781e0b10b..cadeb28b8e47 100644
--- a/fs/netfs/Makefile
+++ b/fs/netfs/Makefile
@@ -5,12 +5,13 @@ netfs-y := \
buffered_write.o \
direct_read.o \
direct_write.o \
- io.o \
iterator.o \
locking.o \
main.o \
misc.o \
objects.o \
+ read_collect.o \
+ read_retry.o \
write_collect.o \
write_issue.o

diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index a688d4c75d99..97d33614553e 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -9,126 +9,6 @@
#include <linux/task_io_accounting_ops.h>
#include "internal.h"

-/*
- * Unlock the folios in a read operation. We need to set PG_writeback on any
- * folios we're going to write back before we unlock them.
- *
- * Note that if the deprecated NETFS_RREQ_USE_PGPRIV2 is set then we use
- * PG_private_2 and do a direct write to the cache from here instead.
- */
-void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
-{
- struct netfs_io_subrequest *subreq;
- struct netfs_folio *finfo;
- struct folio *folio;
- pgoff_t start_page = rreq->start / PAGE_SIZE;
- pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
- size_t account = 0;
- bool subreq_failed = false;
-
- XA_STATE(xas, &rreq->mapping->i_pages, start_page);
-
- if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) {
- __clear_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
- list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
- __clear_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
- }
- }
-
- /* Walk through the pagecache and the I/O request lists simultaneously.
- * We may have a mixture of cached and uncached sections and we only
- * really want to write out the uncached sections. This is slightly
- * complicated by the possibility that we might have huge pages with a
- * mixture inside.
- */
- subreq = list_first_entry(&rreq->subrequests,
- struct netfs_io_subrequest, rreq_link);
- subreq_failed = (subreq->error < 0);
-
- trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
-
- rcu_read_lock();
- xas_for_each(&xas, folio, last_page) {
- loff_t pg_end;
- bool pg_failed = false;
- bool wback_to_cache = false;
- bool folio_started = false;
-
- if (xas_retry(&xas, folio))
- continue;
-
- pg_end = folio_pos(folio) + folio_size(folio) - 1;
-
- for (;;) {
- loff_t sreq_end;
-
- if (!subreq) {
- pg_failed = true;
- break;
- }
- if (test_bit(NETFS_RREQ_USE_PGPRIV2, &rreq->flags)) {
- if (!folio_started && test_bit(NETFS_SREQ_COPY_TO_CACHE,
- &subreq->flags)) {
- trace_netfs_folio(folio, netfs_folio_trace_copy_to_cache);
- folio_start_private_2(folio);
- folio_started = true;
- }
- } else {
- wback_to_cache |=
- test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
- }
- pg_failed |= subreq_failed;
- sreq_end = subreq->start + subreq->len - 1;
- if (pg_end < sreq_end)
- break;
-
- account += subreq->transferred;
- if (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
- subreq = list_next_entry(subreq, rreq_link);
- subreq_failed = (subreq->error < 0);
- } else {
- subreq = NULL;
- subreq_failed = false;
- }
-
- if (pg_end == sreq_end)
- break;
- }
-
- if (!pg_failed) {
- flush_dcache_folio(folio);
- finfo = netfs_folio_info(folio);
- if (finfo) {
- trace_netfs_folio(folio, netfs_folio_trace_filled_gaps);
- if (finfo->netfs_group)
- folio_change_private(folio, finfo->netfs_group);
- else
- folio_detach_private(folio);
- kfree(finfo);
- }
- folio_mark_uptodate(folio);
- if (wback_to_cache && !WARN_ON_ONCE(folio_get_private(folio) != NULL)) {
- trace_netfs_folio(folio, netfs_folio_trace_copy_to_cache);
- folio_attach_private(folio, NETFS_FOLIO_COPY_TO_CACHE);
- filemap_dirty_folio(folio->mapping, folio);
- }
- }
-
- if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
- if (folio->index == rreq->no_unlock_folio &&
- test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
- _debug("no unlock");
- else
- folio_unlock(folio);
- }
- }
- rcu_read_unlock();
-
- task_io_account_read(account);
- if (rreq->netfs_ops->done)
- rreq->netfs_ops->done(rreq);
-}
-
static void netfs_cache_expand_readahead(struct netfs_io_request *rreq,
unsigned long long *_start,
unsigned long long *_len,
@@ -183,6 +63,323 @@ static int netfs_begin_cache_read(struct netfs_io_request *rreq, struct netfs_in
return fscache_begin_read_operation(&rreq->cache_resources, netfs_i_cookie(ctx));
}

+/*
+ * Decant the list of folios to read into a rolling buffer.
+ */
+static size_t netfs_load_buffer_from_ra(struct netfs_io_request *rreq,
+ struct folio_queue *folioq)
+{
+ unsigned int order, nr;
+ size_t size = 0;
+
+ nr = __readahead_batch(rreq->ractl, (struct page **)folioq->vec.folios,
+ ARRAY_SIZE(folioq->vec.folios));
+ folioq->vec.nr = nr;
+ for (int i = 0; i < nr; i++) {
+ struct folio *folio = folioq_folio(folioq, i);
+
+ trace_netfs_folio(folio, netfs_folio_trace_read);
+ order = folio_order(folio);
+ folioq->orders[i] = order;
+ size += PAGE_SIZE << order;
+ }
+
+ for (int i = nr; i < folioq_nr_slots(folioq); i++)
+ folioq_clear(folioq, i);
+
+ return size;
+}
+
+/*
+ * netfs_prepare_read_iterator - Prepare the subreq iterator for I/O
+ * @subreq: The subrequest to be set up
+ *
+ * Prepare the I/O iterator representing the read buffer on a subrequest for
+ * the filesystem to use for I/O (it can be passed directly to a socket). This
+ * is intended to be called from the ->issue_read() method once the filesystem
+ * has trimmed the request to the size it wants.
+ *
+ * Returns the limited size if successful and -ENOMEM if insufficient memory
+ * available.
+ *
+ * [!] NOTE: This must be run in the same thread as ->issue_read() was called
+ * in as we access the readahead_control struct.
+ */
+static ssize_t netfs_prepare_read_iterator(struct netfs_io_subrequest *subreq)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+ size_t rsize;
+
+ rsize = umin(subreq->len, rreq->io_streams[0].sreq_max_len);
+
+ if (rreq->ractl) {
+ /* If we don't have sufficient folios in the rolling buffer,
+ * extract a folioq's worth from the readahead region at a time
+ * into the buffer. Note that this acquires a ref on each page
+ * that we will need to release later - but we don't want to do
+ * that until after we've started the I/O.
+ */
+ while (rreq->submitted < subreq->start + rsize) {
+ struct folio_queue *tail = rreq->buffer_tail, *new;
+ size_t added;
+
+ new = kmalloc(sizeof(*new), GFP_NOFS);
+ if (!new)
+ return -ENOMEM;
+ netfs_stat(&netfs_n_folioq);
+ folioq_init(new);
+ new->prev = tail;
+ tail->next = new;
+ rreq->buffer_tail = new;
+ added = netfs_load_buffer_from_ra(rreq, new);
+ rreq->iter.count += added;
+ rreq->submitted += added;
+ }
+ }
+
+ subreq->len = rsize;
+ if (unlikely(rreq->io_streams[0].sreq_max_segs)) {
+ size_t limit = netfs_limit_iter(&rreq->iter, 0, rsize,
+ rreq->io_streams[0].sreq_max_segs);
+
+ if (limit < rsize) {
+ subreq->len = limit;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_limited);
+ }
+ }
+
+ subreq->io_iter = rreq->iter;
+
+ if (iov_iter_is_folioq(&subreq->io_iter)) {
+ subreq->curr_folioq = (struct folio_queue *)subreq->io_iter.folioq;
+ subreq->curr_folioq_slot = subreq->io_iter.folioq_slot;
+ subreq->curr_folio_order = subreq->curr_folioq->orders[subreq->curr_folioq_slot];
+ }
+
+ iov_iter_truncate(&subreq->io_iter, subreq->len);
+ iov_iter_advance(&rreq->iter, subreq->len);
+ return subreq->len;
+}
+
+static enum netfs_io_source netfs_cache_prepare_read(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq,
+ loff_t i_size)
+{
+ struct netfs_cache_resources *cres = &rreq->cache_resources;
+
+ if (!cres->ops)
+ return NETFS_DOWNLOAD_FROM_SERVER;
+ return cres->ops->prepare_read(subreq, i_size);
+}
+
+static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error,
+ bool was_async)
+{
+ struct netfs_io_subrequest *subreq = priv;
+
+ if (transferred_or_error < 0) {
+ netfs_read_subreq_terminated(subreq, transferred_or_error, was_async);
+ return;
+ }
+
+ if (transferred_or_error > 0)
+ subreq->transferred += transferred_or_error;
+ netfs_read_subreq_terminated(subreq, 0, was_async);
+}
+
+/*
+ * Issue a read against the cache.
+ * - Eats the caller's ref on subreq.
+ */
+static void netfs_read_cache_to_pagecache(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq)
+{
+ struct netfs_cache_resources *cres = &rreq->cache_resources;
+
+ netfs_stat(&netfs_n_rh_read);
+ cres->ops->read(cres, subreq->start, &subreq->io_iter, NETFS_READ_HOLE_IGNORE,
+ netfs_cache_read_terminated, subreq);
+}
+
+/*
+ * Perform a read to the pagecache from a series of sources of different types,
+ * slicing up the region to be read according to available cache blocks and
+ * network rsize.
+ */
+static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
+{
+ struct netfs_inode *ictx = netfs_inode(rreq->inode);
+ unsigned long long start = rreq->start;
+ ssize_t size = rreq->len;
+ int ret = 0;
+
+ atomic_inc(&rreq->nr_outstanding);
+
+ do {
+ struct netfs_io_subrequest *subreq;
+ enum netfs_io_source source = NETFS_DOWNLOAD_FROM_SERVER;
+ ssize_t slice;
+
+ subreq = netfs_alloc_subrequest(rreq);
+ if (!subreq) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ subreq->start = start;
+ subreq->len = size;
+
+ atomic_inc(&rreq->nr_outstanding);
+ spin_lock_bh(&rreq->lock);
+ list_add_tail(&subreq->rreq_link, &rreq->subrequests);
+ subreq->prev_donated = rreq->prev_donated;
+ rreq->prev_donated = 0;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_added);
+ spin_unlock_bh(&rreq->lock);
+
+ source = netfs_cache_prepare_read(rreq, subreq, rreq->i_size);
+ subreq->source = source;
+ if (source == NETFS_DOWNLOAD_FROM_SERVER) {
+ unsigned long long zp = umin(ictx->zero_point, rreq->i_size);
+ size_t len = subreq->len;
+
+ if (subreq->start >= zp) {
+ subreq->source = source = NETFS_FILL_WITH_ZEROES;
+ goto fill_with_zeroes;
+ }
+
+ if (len > zp - subreq->start)
+ len = zp - subreq->start;
+ if (len == 0) {
+ pr_err("ZERO-LEN READ: R=%08x[%x] l=%zx/%zx s=%llx z=%llx i=%llx",
+ rreq->debug_id, subreq->debug_index,
+ subreq->len, size,
+ subreq->start, ictx->zero_point, rreq->i_size);
+ break;
+ }
+ subreq->len = len;
+
+ netfs_stat(&netfs_n_rh_download);
+ if (rreq->netfs_ops->prepare_read) {
+ ret = rreq->netfs_ops->prepare_read(subreq);
+ if (ret < 0) {
+ atomic_dec(&rreq->nr_outstanding);
+ netfs_put_subrequest(subreq, false,
+ netfs_sreq_trace_put_cancel);
+ break;
+ }
+ trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
+ }
+
+ slice = netfs_prepare_read_iterator(subreq);
+ if (slice < 0) {
+ atomic_dec(&rreq->nr_outstanding);
+ netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel);
+ ret = slice;
+ break;
+ }
+
+ rreq->netfs_ops->issue_read(subreq);
+ goto done;
+ }
+
+ fill_with_zeroes:
+ if (source == NETFS_FILL_WITH_ZEROES) {
+ subreq->source = NETFS_FILL_WITH_ZEROES;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
+ netfs_stat(&netfs_n_rh_zero);
+ slice = netfs_prepare_read_iterator(subreq);
+ __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+ netfs_read_subreq_terminated(subreq, 0, false);
+ goto done;
+ }
+
+ if (source == NETFS_READ_FROM_CACHE) {
+ trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
+ slice = netfs_prepare_read_iterator(subreq);
+ netfs_read_cache_to_pagecache(rreq, subreq);
+ goto done;
+ }
+
+ if (source == NETFS_INVALID_READ)
+ break;
+
+ done:
+ size -= slice;
+ start += slice;
+ cond_resched();
+ } while (size > 0);
+
+ if (atomic_dec_and_test(&rreq->nr_outstanding))
+ netfs_rreq_terminated(rreq, false);
+
+ /* Defer error return as we may need to wait for outstanding I/O. */
+ cmpxchg(&rreq->error, 0, ret);
+}
+
+/*
+ * Wait for the read operation to complete, successfully or otherwise.
+ */
+static int netfs_wait_for_read(struct netfs_io_request *rreq)
+{
+ int ret;
+
+ trace_netfs_rreq(rreq, netfs_rreq_trace_wait_ip);
+ wait_on_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS, TASK_UNINTERRUPTIBLE);
+ ret = rreq->error;
+ if (ret == 0 && rreq->submitted < rreq->len) {
+ trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);
+ ret = -EIO;
+ }
+
+ return ret;
+}
+
+/*
+ * Set up the initial folioq of buffer folios in the rolling buffer and set the
+ * iterator to refer to it.
+ */
+static int netfs_prime_buffer(struct netfs_io_request *rreq)
+{
+ struct folio_queue *folioq;
+ size_t added;
+
+ folioq = kmalloc(sizeof(*folioq), GFP_KERNEL);
+ if (!folioq)
+ return -ENOMEM;
+ netfs_stat(&netfs_n_folioq);
+ folioq_init(folioq);
+ rreq->buffer = folioq;
+ rreq->buffer_tail = folioq;
+ rreq->submitted = rreq->start;
+ iov_iter_folio_queue(&rreq->iter, ITER_DEST, folioq, 0, 0, 0);
+
+ added = netfs_load_buffer_from_ra(rreq, folioq);
+ rreq->iter.count += added;
+ rreq->submitted += added;
+ return 0;
+}
+
+/*
+ * Drop the ref on each folio that we inherited from the VM readahead code. We
+ * still have the folio locks to pin the page until we complete the I/O.
+ */
+static void netfs_put_ra_refs(struct folio_queue *folioq)
+{
+ while (folioq) {
+#if 0
+ for (unsigned int slot = 0; slot < folioq_count(folioq); slot++) {
+ if (!folioq_folio(folioq, slot))
+ continue;
+ trace_netfs_folio(folioq_folio(folioq, slot),
+ netfs_folio_trace_read_put);
+ }
+#endif
+ folio_batch_release(&folioq->vec);
+ folioq = folioq->next;
+ }
+}
+
/**
* netfs_readahead - Helper to manage a read request
* @ractl: The description of the readahead request
@@ -201,22 +398,17 @@ static int netfs_begin_cache_read(struct netfs_io_request *rreq, struct netfs_in
void netfs_readahead(struct readahead_control *ractl)
{
struct netfs_io_request *rreq;
- struct netfs_inode *ctx = netfs_inode(ractl->mapping->host);
+ struct netfs_inode *ictx = netfs_inode(ractl->mapping->host);
+ unsigned long long start = readahead_pos(ractl);
+ size_t size = readahead_length(ractl);
int ret;

- _enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
-
- if (readahead_count(ractl) == 0)
- return;
-
- rreq = netfs_alloc_request(ractl->mapping, ractl->file,
- readahead_pos(ractl),
- readahead_length(ractl),
+ rreq = netfs_alloc_request(ractl->mapping, ractl->file, start, size,
NETFS_READAHEAD);
if (IS_ERR(rreq))
return;

- ret = netfs_begin_cache_read(rreq, ctx);
+ ret = netfs_begin_cache_read(rreq, ictx);
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
goto cleanup_free;

@@ -226,18 +418,15 @@ void netfs_readahead(struct readahead_control *ractl)

netfs_rreq_expand(rreq, ractl);

- /* Set up the output buffer */
- iov_iter_xarray(&rreq->iter, ITER_DEST, &ractl->mapping->i_pages,
- rreq->start, rreq->len);
+ rreq->ractl = ractl;
+ if (netfs_prime_buffer(rreq) < 0)
+ goto cleanup_free;
+ netfs_read_to_pagecache(rreq);

- /* Drop the refs on the folios here rather than in the cache or
- * filesystem. The locks will be dropped in netfs_rreq_unlock().
- */
- while (readahead_folio(ractl))
- ;
+ /* Release the folio refs whilst we're waiting for the I/O. */
+ netfs_put_ra_refs(rreq->buffer);

- netfs_begin_read(rreq, false);
- netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
+ netfs_put_request(rreq, true, netfs_rreq_trace_put_return);
return;

cleanup_free:
@@ -246,6 +435,117 @@ void netfs_readahead(struct readahead_control *ractl)
}
EXPORT_SYMBOL(netfs_readahead);

+/*
+ * Create a rolling buffer with a single occupying folio.
+ */
+static int netfs_create_singular_buffer(struct netfs_io_request *rreq, struct folio *folio)
+{
+ struct folio_queue *folioq;
+
+ folioq = kmalloc(sizeof(*folioq), GFP_KERNEL);
+ if (!folioq)
+ return -ENOMEM;
+
+ netfs_stat(&netfs_n_folioq);
+ folioq_init(folioq);
+ folioq_append(folioq, folio);
+ BUG_ON(folioq_folio(folioq, 0) != folio);
+ BUG_ON(folioq_folio_order(folioq, 0) != folio_order(folio));
+ rreq->buffer = folioq;
+ rreq->buffer_tail = folioq;
+ rreq->submitted = rreq->start + rreq->len;
+ iov_iter_folio_queue(&rreq->iter, ITER_DEST, folioq, 0, 0, rreq->len);
+ rreq->ractl = (struct readahead_control *)1UL;
+ return 0;
+}
+
+/*
+ * Read into gaps in a folio partially filled by a streaming write.
+ */
+static int netfs_read_gaps(struct file *file, struct folio *folio)
+{
+ struct netfs_io_request *rreq;
+ struct address_space *mapping = folio->mapping;
+ struct netfs_folio *finfo = netfs_folio_info(folio);
+ struct netfs_inode *ctx = netfs_inode(mapping->host);
+ struct folio *sink = NULL;
+ struct bio_vec *bvec;
+ unsigned int from = finfo->dirty_offset;
+ unsigned int to = from + finfo->dirty_len;
+ unsigned int off = 0, i = 0;
+ size_t flen = folio_size(folio);
+ size_t nr_bvec = flen / PAGE_SIZE + 2;
+ size_t part;
+ int ret;
+
+ _enter("%lx", folio->index);
+
+ rreq = netfs_alloc_request(mapping, file, folio_pos(folio), flen, NETFS_READ_GAPS);
+ if (IS_ERR(rreq)) {
+ ret = PTR_ERR(rreq);
+ goto alloc_error;
+ }
+
+ ret = netfs_begin_cache_read(rreq, ctx);
+ if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
+ goto discard;
+
+ netfs_stat(&netfs_n_rh_read_folio);
+ trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_read_gaps);
+
+ /* Fiddle the buffer so that a gap at the beginning and/or a gap at the
+ * end get copied to, but the middle is discarded.
+ */
+ ret = -ENOMEM;
+ bvec = kmalloc_array(nr_bvec, sizeof(*bvec), GFP_KERNEL);
+ if (!bvec)
+ goto discard;
+
+ sink = folio_alloc(GFP_KERNEL, 0);
+ if (!sink) {
+ kfree(bvec);
+ goto discard;
+ }
+
+ trace_netfs_folio(folio, netfs_folio_trace_read_gaps);
+
+ rreq->direct_bv = bvec;
+ rreq->direct_bv_count = nr_bvec;
+ if (from > 0) {
+ bvec_set_folio(&bvec[i++], folio, from, 0);
+ off = from;
+ }
+ while (off < to) {
+ part = min_t(size_t, to - off, PAGE_SIZE);
+ bvec_set_folio(&bvec[i++], sink, part, 0);
+ off += part;
+ }
+ if (to < flen)
+ bvec_set_folio(&bvec[i++], folio, flen - to, to);
+ iov_iter_bvec(&rreq->iter, ITER_DEST, bvec, i, rreq->len);
+ rreq->submitted = rreq->start + flen;
+
+ netfs_read_to_pagecache(rreq);
+
+ if (sink)
+ folio_put(sink);
+
+ ret = netfs_wait_for_read(rreq);
+ if (ret == 0) {
+ flush_dcache_folio(folio);
+ folio_mark_uptodate(folio);
+ }
+ folio_unlock(folio);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
+ return ret < 0 ? ret : 0;
+
+discard:
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
+alloc_error:
+ folio_unlock(folio);
+ return ret;
+}
+
/**
* netfs_read_folio - Helper to manage a read_folio request
* @file: The file to read from
@@ -265,9 +565,13 @@ int netfs_read_folio(struct file *file, struct folio *folio)
struct address_space *mapping = folio->mapping;
struct netfs_io_request *rreq;
struct netfs_inode *ctx = netfs_inode(mapping->host);
- struct folio *sink = NULL;
int ret;

+ if (folio_test_dirty(folio)) {
+ trace_netfs_folio(folio, netfs_folio_trace_read_gaps);
+ return netfs_read_gaps(file, folio);
+ }
+
_enter("%lx", folio->index);

rreq = netfs_alloc_request(mapping, file,
@@ -286,54 +590,12 @@ int netfs_read_folio(struct file *file, struct folio *folio)
trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);

/* Set up the output buffer */
- if (folio_test_dirty(folio)) {
- /* Handle someone trying to read from an unflushed streaming
- * write. We fiddle the buffer so that a gap at the beginning
- * and/or a gap at the end get copied to, but the middle is
- * discarded.
- */
- struct netfs_folio *finfo = netfs_folio_info(folio);
- struct bio_vec *bvec;
- unsigned int from = finfo->dirty_offset;
- unsigned int to = from + finfo->dirty_len;
- unsigned int off = 0, i = 0;
- size_t flen = folio_size(folio);
- size_t nr_bvec = flen / PAGE_SIZE + 2;
- size_t part;
-
- ret = -ENOMEM;
- bvec = kmalloc_array(nr_bvec, sizeof(*bvec), GFP_KERNEL);
- if (!bvec)
- goto discard;
-
- sink = folio_alloc(GFP_KERNEL, 0);
- if (!sink)
- goto discard;
-
- trace_netfs_folio(folio, netfs_folio_trace_read_gaps);
-
- rreq->direct_bv = bvec;
- rreq->direct_bv_count = nr_bvec;
- if (from > 0) {
- bvec_set_folio(&bvec[i++], folio, from, 0);
- off = from;
- }
- while (off < to) {
- part = min_t(size_t, to - off, PAGE_SIZE);
- bvec_set_folio(&bvec[i++], sink, part, 0);
- off += part;
- }
- if (to < flen)
- bvec_set_folio(&bvec[i++], folio, flen - to, to);
- iov_iter_bvec(&rreq->iter, ITER_DEST, bvec, i, rreq->len);
- } else {
- iov_iter_xarray(&rreq->iter, ITER_DEST, &mapping->i_pages,
- rreq->start, rreq->len);
- }
+ ret = netfs_create_singular_buffer(rreq, folio);
+ if (ret < 0)
+ goto discard;

- ret = netfs_begin_read(rreq, true);
- if (sink)
- folio_put(sink);
+ netfs_read_to_pagecache(rreq);
+ ret = netfs_wait_for_read(rreq);
netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
return ret < 0 ? ret : 0;

@@ -395,7 +657,7 @@ static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,
}

/**
- * netfs_write_begin - Helper to prepare for writing
+ * netfs_write_begin - Helper to prepare for writing [DEPRECATED]
* @ctx: The netfs context
* @file: The file to read from
* @mapping: The mapping to read from
@@ -406,13 +668,10 @@ static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,
*
* Pre-read data for a write-begin request by drawing data from the cache if
* possible, or the netfs if not. Space beyond the EOF is zero-filled.
- * Multiple I/O requests from different sources will get munged together. If
- * necessary, the readahead window can be expanded in either direction to a
- * more convenient alighment for RPC efficiency or to make storage in the cache
- * feasible.
+ * Multiple I/O requests from different sources will get munged together.
*
* The calling netfs must provide a table of operations, only one of which,
- * issue_op, is mandatory.
+ * issue_read, is mandatory.
*
* The check_write_begin() operation can be provided to check for and flush
* conflicting writes once the folio is grabbed and locked. It is passed a
@@ -437,8 +696,6 @@ int netfs_write_begin(struct netfs_inode *ctx,
pgoff_t index = pos >> PAGE_SHIFT;
int ret;

- DEFINE_READAHEAD(ractl, file, NULL, mapping, index);
-
retry:
folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
mapping_gfp_mask(mapping));
@@ -486,22 +743,13 @@ int netfs_write_begin(struct netfs_inode *ctx,
netfs_stat(&netfs_n_rh_write_begin);
trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);

- /* Expand the request to meet caching requirements and download
- * preferences.
- */
- ractl._nr_pages = folio_nr_pages(folio);
- netfs_rreq_expand(rreq, &ractl);
-
/* Set up the output buffer */
- iov_iter_xarray(&rreq->iter, ITER_DEST, &mapping->i_pages,
- rreq->start, rreq->len);
-
- /* We hold the folio locks, so we can drop the references */
- folio_get(folio);
- while (readahead_folio(&ractl))
- ;
+ ret = netfs_create_singular_buffer(rreq, folio);
+ if (ret < 0)
+ goto error_put;

- ret = netfs_begin_read(rreq, true);
+ netfs_read_to_pagecache(rreq);
+ ret = netfs_wait_for_read(rreq);
if (ret < 0)
goto error;
netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
@@ -557,10 +805,13 @@ int netfs_prefetch_for_write(struct file *file, struct folio *folio,
trace_netfs_read(rreq, start, flen, netfs_read_trace_prefetch_for_write);

/* Set up the output buffer */
- iov_iter_xarray(&rreq->iter, ITER_DEST, &mapping->i_pages,
- rreq->start, rreq->len);
+ ret = netfs_create_singular_buffer(rreq, folio);
+ if (ret < 0)
+ goto error_put;

- ret = netfs_begin_read(rreq, true);
+ folioq_mark2(rreq->buffer, 0);
+ netfs_read_to_pagecache(rreq);
+ ret = netfs_wait_for_read(rreq);
netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
return ret;

diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c
index 10a1e4da6bda..b1a66a6e6bc2 100644
--- a/fs/netfs/direct_read.c
+++ b/fs/netfs/direct_read.c
@@ -16,6 +16,143 @@
#include <linux/netfs.h>
#include "internal.h"

+static void netfs_prepare_dio_read_iterator(struct netfs_io_subrequest *subreq)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+ size_t rsize;
+
+ rsize = umin(subreq->len, rreq->io_streams[0].sreq_max_len);
+ subreq->len = rsize;
+
+ if (unlikely(rreq->io_streams[0].sreq_max_segs)) {
+ size_t limit = netfs_limit_iter(&rreq->iter, 0, rsize,
+ rreq->io_streams[0].sreq_max_segs);
+
+ if (limit < rsize) {
+ subreq->len = limit;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_limited);
+ }
+ }
+
+ trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
+
+ subreq->io_iter = rreq->iter;
+ iov_iter_truncate(&subreq->io_iter, subreq->len);
+ iov_iter_advance(&rreq->iter, subreq->len);
+}
+
+/*
+ * Perform a read to a buffer from the server, slicing up the region to be read
+ * according to the network rsize.
+ */
+static int netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq)
+{
+ unsigned long long start = rreq->start;
+ ssize_t size = rreq->len;
+ int ret = 0;
+
+ atomic_set(&rreq->nr_outstanding, 1);
+
+ do {
+ struct netfs_io_subrequest *subreq;
+ ssize_t slice;
+
+ subreq = netfs_alloc_subrequest(rreq);
+ if (!subreq) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
+ subreq->start = start;
+ subreq->len = size;
+
+ atomic_inc(&rreq->nr_outstanding);
+ spin_lock_bh(&rreq->lock);
+ list_add_tail(&subreq->rreq_link, &rreq->subrequests);
+ subreq->prev_donated = rreq->prev_donated;
+ rreq->prev_donated = 0;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_added);
+ spin_unlock_bh(&rreq->lock);
+
+ netfs_stat(&netfs_n_rh_download);
+ if (rreq->netfs_ops->prepare_read) {
+ ret = rreq->netfs_ops->prepare_read(subreq);
+ if (ret < 0) {
+ atomic_dec(&rreq->nr_outstanding);
+ netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel);
+ break;
+ }
+ }
+
+ netfs_prepare_dio_read_iterator(subreq);
+ slice = subreq->len;
+ rreq->netfs_ops->issue_read(subreq);
+
+ size -= slice;
+ start += slice;
+ rreq->submitted += slice;
+
+ if (test_bit(NETFS_RREQ_BLOCKED, &rreq->flags) &&
+ test_bit(NETFS_RREQ_NONBLOCK, &rreq->flags))
+ break;
+ cond_resched();
+ } while (size > 0);
+
+ if (atomic_dec_and_test(&rreq->nr_outstanding))
+ netfs_rreq_terminated(rreq, false);
+ return ret;
+}
+
+/*
+ * Perform a read to an application buffer, bypassing the pagecache and the
+ * local disk cache.
+ */
+static int netfs_unbuffered_read(struct netfs_io_request *rreq, bool sync)
+{
+ int ret;
+
+ _enter("R=%x %llx-%llx",
+ rreq->debug_id, rreq->start, rreq->start + rreq->len - 1);
+
+ if (rreq->len == 0) {
+ pr_err("Zero-sized read [R=%x]\n", rreq->debug_id);
+ return -EIO;
+ }
+
+ // TODO: Use bounce buffer if requested
+
+ inode_dio_begin(rreq->inode);
+
+ ret = netfs_dispatch_unbuffered_reads(rreq);
+
+ if (!rreq->submitted) {
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_no_submit);
+ inode_dio_end(rreq->inode);
+ ret = 0;
+ goto out;
+ }
+
+ if (sync) {
+ trace_netfs_rreq(rreq, netfs_rreq_trace_wait_ip);
+ wait_on_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS,
+ TASK_UNINTERRUPTIBLE);
+
+ ret = rreq->error;
+ if (ret == 0 && rreq->submitted < rreq->len &&
+ rreq->origin != NETFS_DIO_READ) {
+ trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);
+ ret = -EIO;
+ }
+ } else {
+ ret = -EIOCBQUEUED;
+ }
+
+out:
+ _leave(" = %d", ret);
+ return ret;
+}
+
/**
* netfs_unbuffered_read_iter_locked - Perform an unbuffered or direct I/O read
* @iocb: The I/O control descriptor describing the read
@@ -31,7 +168,7 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i
struct netfs_io_request *rreq;
ssize_t ret;
size_t orig_count = iov_iter_count(iter);
- bool async = !is_sync_kiocb(iocb);
+ bool sync = is_sync_kiocb(iocb);

_enter("");

@@ -78,13 +215,13 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i

// TODO: Set up bounce buffer if needed

- if (async)
+ if (!sync)
rreq->iocb = iocb;

- ret = netfs_begin_read(rreq, is_sync_kiocb(iocb));
+ ret = netfs_unbuffered_read(rreq, sync);
if (ret < 0)
goto out; /* May be -EIOCBQUEUED */
- if (!async) {
+ if (sync) {
// TODO: Copy from bounce buffer
iocb->ki_pos += rreq->transferred;
ret = rreq->transferred;
@@ -94,8 +231,6 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i
netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
if (ret > 0)
orig_count -= ret;
- if (ret != -EIOCBQUEUED)
- iov_iter_revert(iter, orig_count - iov_iter_count(iter));
return ret;
}
EXPORT_SYMBOL(netfs_unbuffered_read_iter_locked);
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 21a3c7d13585..a4ee0cebf014 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -23,16 +23,9 @@
/*
* buffered_read.c
*/
-void netfs_rreq_unlock_folios(struct netfs_io_request *rreq);
int netfs_prefetch_for_write(struct file *file, struct folio *folio,
size_t offset, size_t len);

-/*
- * io.c
- */
-void netfs_rreq_work(struct work_struct *work);
-int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
-
/*
* main.c
*/
@@ -90,6 +83,18 @@ static inline void netfs_see_request(struct netfs_io_request *rreq,
trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), what);
}

+/*
+ * read_collect.c
+ */
+void netfs_read_termination_worker(struct work_struct *work);
+void netfs_rreq_terminated(struct netfs_io_request *rreq, bool was_async);
+
+/*
+ * read_retry.c
+ */
+void netfs_retry_reads(struct netfs_io_request *rreq);
+void netfs_unlock_abandoned_read_pages(struct netfs_io_request *rreq);
+
/*
* stats.c
*/
diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c
index b781bbbf1d8d..72a435e5fc6d 100644
--- a/fs/netfs/iterator.c
+++ b/fs/netfs/iterator.c
@@ -188,9 +188,59 @@ static size_t netfs_limit_xarray(const struct iov_iter *iter, size_t start_offse
return min(span, max_size);
}

+/*
+ * Select the span of a folio queue iterator we're going to use. Limit it by
+ * both maximum size and maximum number of segments. Returns the size of the
+ * span in bytes.
+ */
+static size_t netfs_limit_folioq(const struct iov_iter *iter, size_t start_offset,
+ size_t max_size, size_t max_segs)
+{
+ const struct folio_queue *folioq = iter->folioq;
+ unsigned int nsegs = 0;
+ unsigned int slot = iter->folioq_slot;
+ size_t span = 0, n = iter->count;
+
+ if (WARN_ON(!iov_iter_is_folioq(iter)) ||
+ WARN_ON(start_offset > n) ||
+ n == 0)
+ return 0;
+ max_size = umin(max_size, n - start_offset);
+
+ if (slot >= folioq_nr_slots(folioq)) {
+ folioq = folioq->next;
+ slot = 0;
+ }
+
+ start_offset += iter->iov_offset;
+ do {
+ size_t flen = folioq_folio_size(folioq, slot);
+
+ if (start_offset < flen) {
+ span += flen - start_offset;
+ nsegs++;
+ start_offset = 0;
+ } else {
+ start_offset -= flen;
+ }
+ if (span >= max_size || nsegs >= max_segs)
+ break;
+
+ slot++;
+ if (slot >= folioq_nr_slots(folioq)) {
+ folioq = folioq->next;
+ slot = 0;
+ }
+ } while (folioq);
+
+ return umin(span, max_size);
+}
+
size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
size_t max_size, size_t max_segs)
{
+ if (iov_iter_is_folioq(iter))
+ return netfs_limit_folioq(iter, start_offset, max_size, max_segs);
if (iov_iter_is_bvec(iter))
return netfs_limit_bvec(iter, start_offset, max_size, max_segs);
if (iov_iter_is_xarray(iter))
diff --git a/fs/netfs/main.c b/fs/netfs/main.c
index 1ee712bb3610..ca416235bdf7 100644
--- a/fs/netfs/main.c
+++ b/fs/netfs/main.c
@@ -36,6 +36,7 @@ DEFINE_SPINLOCK(netfs_proc_lock);
static const char *netfs_origins[nr__netfs_io_origin] = {
[NETFS_READAHEAD] = "RA",
[NETFS_READPAGE] = "RP",
+ [NETFS_READ_GAPS] = "RG",
[NETFS_READ_FOR_WRITE] = "RW",
[NETFS_DIO_READ] = "DR",
[NETFS_WRITEBACK] = "WB",
@@ -61,7 +62,7 @@ static int netfs_requests_seq_show(struct seq_file *m, void *v)

rreq = list_entry(v, struct netfs_io_request, proc_link);
seq_printf(m,
- "%08x %s %3d %2lx %4d %3d @%04llx %llx/%llx",
+ "%08x %s %3d %2lx %4ld %3d @%04llx %llx/%llx",
rreq->debug_id,
netfs_origins[rreq->origin],
refcount_read(&rreq->ref),
diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index 9d2563d4dab8..da8314c48483 100644
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -40,7 +40,6 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
memset(rreq, 0, kmem_cache_size(cache));
rreq->start = start;
rreq->len = len;
- rreq->upper_len = len;
rreq->origin = origin;
rreq->netfs_ops = ctx->ops;
rreq->mapping = mapping;
@@ -48,6 +47,8 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
rreq->i_size = i_size_read(inode);
rreq->debug_id = atomic_inc_return(&debug_ids);
rreq->wsize = INT_MAX;
+ rreq->io_streams[0].sreq_max_len = ULONG_MAX;
+ rreq->io_streams[0].sreq_max_segs = 0;
spin_lock_init(&rreq->lock);
INIT_LIST_HEAD(&rreq->io_streams[0].subrequests);
INIT_LIST_HEAD(&rreq->io_streams[1].subrequests);
@@ -56,9 +57,10 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,

if (origin == NETFS_READAHEAD ||
origin == NETFS_READPAGE ||
+ origin == NETFS_READ_GAPS ||
origin == NETFS_READ_FOR_WRITE ||
origin == NETFS_DIO_READ)
- INIT_WORK(&rreq->work, netfs_rreq_work);
+ INIT_WORK(&rreq->work, netfs_read_termination_worker);
else
INIT_WORK(&rreq->work, netfs_write_collection_worker);

@@ -173,7 +175,7 @@ void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
if (was_async) {
rreq->work.func = netfs_free_request;
if (!queue_work(system_unbound_wq, &rreq->work))
- BUG();
+ WARN_ON(1);
} else {
netfs_free_request(&rreq->work);
}
diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
new file mode 100644
index 000000000000..f9907907106c
--- /dev/null
+++ b/fs/netfs/read_collect.c
@@ -0,0 +1,540 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Network filesystem read subrequest result collection, assessment and
+ * retrying.
+ *
+ * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/task_io_accounting_ops.h>
+#include "internal.h"
+
+/*
+ * Clear the unread part of an I/O request.
+ */
+static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
+{
+ netfs_reset_iter(subreq);
+ WARN_ON_ONCE(subreq->len - subreq->transferred != iov_iter_count(&subreq->io_iter));
+ iov_iter_zero(iov_iter_count(&subreq->io_iter), &subreq->io_iter);
+ if (subreq->start + subreq->transferred >= subreq->rreq->i_size)
+ __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
+}
+
+/*
+ * Flush, mark and unlock a folio that's now completely read. If we want to
+ * cache the folio, we set the group to NETFS_FOLIO_COPY_TO_CACHE, mark it
+ * dirty and let writeback handle it.
+ */
+static void netfs_unlock_read_folio(struct netfs_io_subrequest *subreq,
+ struct netfs_io_request *rreq,
+ struct folio *folio)
+{
+ struct netfs_folio *finfo;
+
+ flush_dcache_folio(folio);
+ folio_mark_uptodate(folio);
+
+ if (!test_bit(NETFS_RREQ_USE_PGPRIV2, &rreq->flags)) {
+ finfo = netfs_folio_info(folio);
+ if (finfo) {
+ trace_netfs_folio(folio, netfs_folio_trace_filled_gaps);
+ if (finfo->netfs_group)
+ folio_change_private(folio, finfo->netfs_group);
+ else
+ folio_detach_private(folio);
+ kfree(finfo);
+ }
+
+ if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags)) {
+ if (!WARN_ON_ONCE(folio_get_private(folio) != NULL)) {
+ trace_netfs_folio(folio, netfs_folio_trace_copy_to_cache);
+ folio_attach_private(folio, NETFS_FOLIO_COPY_TO_CACHE);
+ folio_mark_dirty(folio);
+ }
+ } else {
+ trace_netfs_folio(folio, netfs_folio_trace_read_done);
+ }
+ } else {
+ // TODO: Use of PG_private_2 is deprecated.
+ if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags)) {
+ trace_netfs_folio(folio, netfs_folio_trace_copy_to_cache);
+ folio_start_private_2(folio);
+ }
+ }
+
+ if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
+ if (folio->index == rreq->no_unlock_folio &&
+ test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
+ _debug("no unlock");
+ else
+ folio_unlock(folio);
+ }
+}
+
+/*
+ * Unlock any folios that are now completely read. Returns true if the
+ * subrequest is removed from the list.
+ */
+static bool netfs_consume_read_data(struct netfs_io_subrequest *subreq, bool was_async)
+{
+ struct netfs_io_subrequest *prev, *next;
+ struct netfs_io_request *rreq = subreq->rreq;
+ struct folio_queue *folioq = subreq->curr_folioq;
+ size_t avail, prev_donated, next_donated, fsize, part, excess;
+ loff_t fpos, start;
+ loff_t fend;
+ int slot = subreq->curr_folioq_slot;
+
+ if (WARN(subreq->transferred > subreq->len,
+ "Subreq overread: R%x[%x] %zu > %zu",
+ rreq->debug_id, subreq->debug_index,
+ subreq->transferred, subreq->len))
+ subreq->transferred = subreq->len;
+
+next_folio:
+ fsize = PAGE_SIZE << subreq->curr_folio_order;
+ fpos = round_down(subreq->start + subreq->consumed, fsize);
+ fend = fpos + fsize;
+
+ if (WARN_ON_ONCE(!folioq) ||
+ WARN_ON_ONCE(!folioq_folio(folioq, slot)) ||
+ WARN_ON_ONCE(folioq_folio(folioq, slot)->index != fpos / PAGE_SIZE)) {
+ pr_err("R=%08x[%x] s=%llx-%llx ctl=%zx/%zx/%zx sl=%u\n",
+ rreq->debug_id, subreq->debug_index,
+ subreq->start, subreq->start + subreq->transferred - 1,
+ subreq->consumed, subreq->transferred, subreq->len,
+ slot);
+ if (folioq) {
+ struct folio *folio = folioq_folio(folioq, slot);
+
+ pr_err("folioq: %02x%02x%02x%02x\n",
+ folioq->orders[0], folioq->orders[1],
+ folioq->orders[2], folioq->orders[3]);
+ if (folio)
+ pr_err("folio: %llx-%llx ix=%llx o=%u qo=%u\n",
+ fpos, fend - 1, folio_pos(folio), folio_order(folio),
+ folioq_folio_order(folioq, slot));
+ }
+ }
+
+donation_changed:
+ /* Try to consume the current folio if we've hit or passed the end of
+ * it. There's a possibility that this subreq doesn't start at the
+ * beginning of the folio, in which case we need to donate to/from the
+ * preceding subreq.
+ *
+ * We also need to include any potential donation back from the
+ * following subreq.
+ */
+ prev_donated = READ_ONCE(subreq->prev_donated);
+ next_donated = READ_ONCE(subreq->next_donated);
+ if (prev_donated || next_donated) {
+ spin_lock_bh(&rreq->lock);
+ prev_donated = subreq->prev_donated;
+ next_donated = subreq->next_donated;
+ subreq->start -= prev_donated;
+ subreq->len += prev_donated;
+ subreq->transferred += prev_donated;
+ prev_donated = subreq->prev_donated = 0;
+ if (subreq->transferred == subreq->len) {
+ subreq->len += next_donated;
+ subreq->transferred += next_donated;
+ next_donated = subreq->next_donated = 0;
+ }
+ trace_netfs_sreq(subreq, netfs_sreq_trace_add_donations);
+ spin_unlock_bh(&rreq->lock);
+ }
+
+ avail = subreq->transferred;
+ if (avail == subreq->len)
+ avail += next_donated;
+ start = subreq->start;
+ if (subreq->consumed == 0) {
+ start -= prev_donated;
+ avail += prev_donated;
+ } else {
+ start += subreq->consumed;
+ avail -= subreq->consumed;
+ }
+ part = umin(avail, fsize);
+
+ trace_netfs_progress(subreq, start, avail, part);
+
+ if (start + avail >= fend) {
+ if (fpos == start) {
+ /* Flush, unlock and mark for caching any folio we've just read. */
+ subreq->consumed = fend - subreq->start;
+ netfs_unlock_read_folio(subreq, rreq, folioq_folio(folioq, slot));
+ folioq_mark2(folioq, slot);
+ if (subreq->consumed >= subreq->len)
+ goto remove_subreq;
+ } else if (fpos < start) {
+ excess = fend - subreq->start;
+
+ spin_lock_bh(&rreq->lock);
+ /* If we complete first on a folio split with the
+ * preceding subreq, donate to that subreq - otherwise
+ * we get the responsibility.
+ */
+ if (subreq->prev_donated != prev_donated) {
+ spin_unlock_bh(&rreq->lock);
+ goto donation_changed;
+ }
+
+ if (list_is_first(&subreq->rreq_link, &rreq->subrequests)) {
+ spin_unlock_bh(&rreq->lock);
+ pr_err("Can't donate prior to front\n");
+ goto bad;
+ }
+
+ prev = list_prev_entry(subreq, rreq_link);
+ WRITE_ONCE(prev->next_donated, prev->next_donated + excess);
+ subreq->start += excess;
+ subreq->len -= excess;
+ subreq->transferred -= excess;
+ trace_netfs_donate(rreq, subreq, prev, excess,
+ netfs_trace_donate_tail_to_prev);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_donate_to_prev);
+
+ if (subreq->consumed >= subreq->len)
+ goto remove_subreq_locked;
+ spin_unlock_bh(&rreq->lock);
+ } else {
+ pr_err("fpos > start\n");
+ goto bad;
+ }
+
+ /* Advance the rolling buffer to the next folio. */
+ slot++;
+ if (slot >= folioq_nr_slots(folioq)) {
+ slot = 0;
+ folioq = folioq->next;
+ subreq->curr_folioq = folioq;
+ }
+ subreq->curr_folioq_slot = slot;
+ if (folioq && folioq_folio(folioq, slot))
+ subreq->curr_folio_order = folioq->orders[slot];
+ if (!was_async)
+ cond_resched();
+ goto next_folio;
+ }
+
+ /* Deal with partial progress. */
+ if (subreq->transferred < subreq->len)
+ return false;
+
+ /* Donate the remaining downloaded data to one of the neighbouring
+ * subrequests. Note that we may race with them doing the same thing.
+ */
+ spin_lock_bh(&rreq->lock);
+
+ if (subreq->prev_donated != prev_donated ||
+ subreq->next_donated != next_donated) {
+ spin_unlock_bh(&rreq->lock);
+ cond_resched();
+ goto donation_changed;
+ }
+
+ /* Deal with the trickiest case: that this subreq is in the middle of a
+ * folio, not touching either edge, but finishes first. In such a
+ * case, we donate to the previous subreq, if there is one, so that the
+ * donation is only handled when that completes - and remove this
+ * subreq from the list.
+ *
+ * If the previous subreq finished first, we will have acquired their
+ * donation and should be able to unlock folios and/or donate nextwards.
+ */
+ if (!subreq->consumed &&
+ !prev_donated &&
+ !list_is_first(&subreq->rreq_link, &rreq->subrequests)) {
+ prev = list_prev_entry(subreq, rreq_link);
+ WRITE_ONCE(prev->next_donated, prev->next_donated + subreq->len);
+ subreq->start += subreq->len;
+ subreq->len = 0;
+ subreq->transferred = 0;
+ trace_netfs_donate(rreq, subreq, prev, subreq->len,
+ netfs_trace_donate_to_prev);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_donate_to_prev);
+ goto remove_subreq_locked;
+ }
+
+ /* If we can't donate down the chain, donate up the chain instead. */
+ excess = subreq->len - subreq->consumed + next_donated;
+
+ if (!subreq->consumed)
+ excess += prev_donated;
+
+ if (list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
+ rreq->prev_donated = excess;
+ trace_netfs_donate(rreq, subreq, NULL, excess,
+ netfs_trace_donate_to_deferred_next);
+ } else {
+ next = list_next_entry(subreq, rreq_link);
+ WRITE_ONCE(next->prev_donated, excess);
+ trace_netfs_donate(rreq, subreq, next, excess,
+ netfs_trace_donate_to_next);
+ }
+ trace_netfs_sreq(subreq, netfs_sreq_trace_donate_to_next);
+ subreq->len = subreq->consumed;
+ subreq->transferred = subreq->consumed;
+ goto remove_subreq_locked;
+
+remove_subreq:
+ spin_lock_bh(&rreq->lock);
+remove_subreq_locked:
+ subreq->consumed = subreq->len;
+ list_del(&subreq->rreq_link);
+ spin_unlock_bh(&rreq->lock);
+ netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_consumed);
+ return true;
+
+bad:
+ /* Errr... prev and next both donated to us, but insufficient to finish
+ * the folio.
+ */
+ printk("R=%08x[%x] s=%llx-%llx %zx/%zx/%zx\n",
+ rreq->debug_id, subreq->debug_index,
+ subreq->start, subreq->start + subreq->transferred - 1,
+ subreq->consumed, subreq->transferred, subreq->len);
+ printk("folio: %llx-%llx\n", fpos, fend - 1);
+ printk("donated: prev=%zx next=%zx\n", prev_donated, next_donated);
+ printk("s=%llx av=%zx part=%zx\n", start, avail, part);
+ BUG();
+}
+
+/*
+ * Do page flushing and suchlike after DIO.
+ */
+static void netfs_rreq_assess_dio(struct netfs_io_request *rreq)
+{
+ struct netfs_io_subrequest *subreq;
+ unsigned int i;
+
+ /* Collect unbuffered reads and direct reads, adding up the transfer
+ * sizes until we find the first short or failed subrequest.
+ */
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ rreq->transferred += subreq->transferred;
+
+ if (subreq->transferred < subreq->len ||
+ test_bit(NETFS_SREQ_FAILED, &subreq->flags)) {
+ rreq->error = subreq->error;
+ break;
+ }
+ }
+
+ if (rreq->origin == NETFS_DIO_READ) {
+ for (i = 0; i < rreq->direct_bv_count; i++) {
+ flush_dcache_page(rreq->direct_bv[i].bv_page);
+ // TODO: cifs marks pages in the destination buffer
+ // dirty under some circumstances after a read. Do we
+ // need to do that too?
+ set_page_dirty(rreq->direct_bv[i].bv_page);
+ }
+ }
+
+ if (rreq->iocb) {
+ rreq->iocb->ki_pos += rreq->transferred;
+ if (rreq->iocb->ki_complete)
+ rreq->iocb->ki_complete(
+ rreq->iocb, rreq->error ? rreq->error : rreq->transferred);
+ }
+ if (rreq->netfs_ops->done)
+ rreq->netfs_ops->done(rreq);
+ if (rreq->origin == NETFS_DIO_READ)
+ inode_dio_end(rreq->inode);
+}
+
+/*
+ * Assess the state of a read request and decide what to do next.
+ *
+ * Note that we could be in an ordinary kernel thread, on a workqueue or in
+ * softirq context at this point. We inherit a ref from the caller.
+ */
+static void netfs_rreq_assess(struct netfs_io_request *rreq)
+{
+ trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
+
+ //netfs_rreq_is_still_valid(rreq);
+
+ if (test_and_clear_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags)) {
+ netfs_retry_reads(rreq);
+ return;
+ }
+
+ if (rreq->origin == NETFS_DIO_READ ||
+ rreq->origin == NETFS_READ_GAPS)
+ netfs_rreq_assess_dio(rreq);
+ task_io_account_read(rreq->transferred);
+
+ trace_netfs_rreq(rreq, netfs_rreq_trace_wake_ip);
+ clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+ wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
+
+ trace_netfs_rreq(rreq, netfs_rreq_trace_done);
+ netfs_clear_subrequests(rreq, false);
+ netfs_unlock_abandoned_read_pages(rreq);
+}
+
+void netfs_read_termination_worker(struct work_struct *work)
+{
+ struct netfs_io_request *rreq =
+ container_of(work, struct netfs_io_request, work);
+ netfs_see_request(rreq, netfs_rreq_trace_see_work);
+ netfs_rreq_assess(rreq);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_work_complete);
+}
+
+/*
+ * Handle the completion of all outstanding I/O operations on a read request.
+ * We inherit a ref from the caller.
+ */
+void netfs_rreq_terminated(struct netfs_io_request *rreq, bool was_async)
+{
+ if (!was_async)
+ return netfs_rreq_assess(rreq);
+ if (!work_pending(&rreq->work)) {
+ netfs_get_request(rreq, netfs_rreq_trace_get_work);
+ if (!queue_work(system_unbound_wq, &rreq->work))
+ netfs_put_request(rreq, was_async, netfs_rreq_trace_put_work_nq);
+ }
+}
+
+/**
+ * netfs_read_subreq_progress - Note progress of a read operation.
+ * @subreq: The read request that has terminated.
+ * @was_async: True if we're in an asynchronous context.
+ *
+ * This tells the read side of netfs lib that a contributory I/O operation has
+ * made some progress and that it may be possible to unlock some folios.
+ *
+ * Before calling, the filesystem should update subreq->transferred to track
+ * the amount of data copied into the output buffer.
+ *
+ * If @was_async is true, the caller might be running in softirq or interrupt
+ * context and we can't sleep.
+ */
+void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq,
+ bool was_async)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+
+ trace_netfs_sreq(subreq, netfs_sreq_trace_progress);
+
+ if (subreq->transferred > subreq->consumed &&
+ (rreq->origin == NETFS_READAHEAD ||
+ rreq->origin == NETFS_READPAGE ||
+ rreq->origin == NETFS_READ_FOR_WRITE)) {
+ netfs_consume_read_data(subreq, was_async);
+ __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+ }
+}
+EXPORT_SYMBOL(netfs_read_subreq_progress);
+
+/**
+ * netfs_read_subreq_terminated - Note the termination of an I/O operation.
+ * @subreq: The I/O request that has terminated.
+ * @error: Error code indicating type of completion.
+ * @was_async: The termination was asynchronous
+ *
+ * This tells the read helper that a contributory I/O operation has terminated,
+ * one way or another, and that it should integrate the results.
+ *
+ * The caller indicates the outcome of the operation through @error, supplying
+ * 0 to indicate a successful or retryable transfer (if NETFS_SREQ_NEED_RETRY
+ * is set) or a negative error code. The helper will look after reissuing I/O
+ * operations as appropriate and writing downloaded data to the cache.
+ *
+ * Before calling, the filesystem should update subreq->transferred to track
+ * the amount of data copied into the output buffer.
+ *
+ * If @was_async is true, the caller might be running in softirq or interrupt
+ * context and we can't sleep.
+ */
+void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
+ int error, bool was_async)
+{
+ struct netfs_io_request *rreq = subreq->rreq;
+
+ switch (subreq->source) {
+ case NETFS_READ_FROM_CACHE:
+ netfs_stat(&netfs_n_rh_read_done);
+ break;
+ case NETFS_DOWNLOAD_FROM_SERVER:
+ netfs_stat(&netfs_n_rh_download_done);
+ break;
+ default:
+ break;
+ }
+
+ if (rreq->origin != NETFS_DIO_READ) {
+ /* Collect buffered reads.
+ *
+ * If the read completed validly short, then we can clear the
+ * tail before going on to unlock the folios.
+ */
+ if (error == 0 && subreq->transferred < subreq->len &&
+ (test_bit(NETFS_SREQ_HIT_EOF, &subreq->flags) ||
+ test_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags))) {
+ netfs_clear_unread(subreq);
+ subreq->transferred = subreq->len;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_clear);
+ }
+ if (subreq->transferred > subreq->consumed &&
+ (rreq->origin == NETFS_READAHEAD ||
+ rreq->origin == NETFS_READPAGE ||
+ rreq->origin == NETFS_READ_FOR_WRITE)) {
+ netfs_consume_read_data(subreq, was_async);
+ __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+ }
+ rreq->transferred += subreq->transferred;
+ }
+
+ /* Deal with retry requests, short reads and errors. If we retry
+ * but don't make progress, we abandon the attempt.
+ */
+ if (!error && subreq->transferred < subreq->len) {
+ if (test_bit(NETFS_SREQ_HIT_EOF, &subreq->flags)) {
+ trace_netfs_sreq(subreq, netfs_sreq_trace_hit_eof);
+ } else {
+ trace_netfs_sreq(subreq, netfs_sreq_trace_short);
+ if (subreq->transferred > subreq->consumed) {
+ __set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ __clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+ set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
+ } else if (!__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
+ __set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ set_bit(NETFS_RREQ_NEED_RETRY, &rreq->flags);
+ } else {
+ __set_bit(NETFS_SREQ_FAILED, &subreq->flags);
+ error = -ENODATA;
+ }
+ }
+ }
+
+ subreq->error = error;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
+
+ if (unlikely(error < 0)) {
+ trace_netfs_failure(rreq, subreq, error, netfs_fail_read);
+ if (subreq->source == NETFS_READ_FROM_CACHE) {
+ netfs_stat(&netfs_n_rh_read_failed);
+ } else {
+ netfs_stat(&netfs_n_rh_download_failed);
+ set_bit(NETFS_RREQ_FAILED, &rreq->flags);
+ rreq->error = subreq->error;
+ }
+ }
+
+ if (atomic_dec_and_test(&rreq->nr_outstanding))
+ netfs_rreq_terminated(rreq, was_async);
+
+ netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
+}
+EXPORT_SYMBOL(netfs_read_subreq_terminated);
diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c
new file mode 100644
index 000000000000..0350592ea804
--- /dev/null
+++ b/fs/netfs/read_retry.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Network filesystem read subrequest retrying.
+ *
+ * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+static void netfs_reissue_read(struct netfs_io_request *rreq,
+ struct netfs_io_subrequest *subreq)
+{
+ struct iov_iter *io_iter = &subreq->io_iter;
+
+ if (iov_iter_is_folioq(io_iter)) {
+ subreq->curr_folioq = (struct folio_queue *)io_iter->folioq;
+ subreq->curr_folioq_slot = io_iter->folioq_slot;
+ subreq->curr_folio_order = subreq->curr_folioq->orders[subreq->curr_folioq_slot];
+ }
+
+ atomic_inc(&rreq->nr_outstanding);
+ __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
+ netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
+ subreq->rreq->netfs_ops->issue_read(subreq);
+}
+
+/*
+ * Go through the list of failed/short reads, retrying all retryable ones. We
+ * need to switch failed cache reads to network downloads.
+ */
+static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
+{
+ struct netfs_io_subrequest *subreq;
+ struct netfs_io_stream *stream0 = &rreq->io_streams[0];
+ LIST_HEAD(sublist);
+ LIST_HEAD(queue);
+
+ _enter("R=%x", rreq->debug_id);
+
+ if (list_empty(&rreq->subrequests))
+ return;
+
+ if (rreq->netfs_ops->retry_request)
+ rreq->netfs_ops->retry_request(rreq, NULL);
+
+ /* If there's no renegotiation to do, just resend each retryable subreq
+ * up to the first permanently failed one.
+ */
+ if (!rreq->netfs_ops->prepare_read &&
+ !test_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags)) {
+ struct netfs_io_subrequest *subreq;
+
+ list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+ if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
+ break;
+ if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
+ netfs_reset_iter(subreq);
+ netfs_reissue_read(rreq, subreq);
+ }
+ }
+ return;
+ }
+
+ /* Okay, we need to renegotiate all the download requests and flip any
+ * failed cache reads over to being download requests and negotiate
+ * those also. All fully successful subreqs have been removed from the
+ * list and any spare data from those has been donated.
+ *
+ * What we do is decant the list and rebuild it one subreq at a time so
+ * that we don't end up with donations jumping over a gap we're busy
+ * populating with smaller subrequests. In the event that the subreq
+ * we just launched finishes before we insert the next subreq, it'll
+ * fill in rreq->prev_donated instead.
+
+ * Note: Alternatively, we could split the tail subrequest right before
+ * we reissue it and fix up the donations under lock.
+ */
+ list_splice_init(&rreq->subrequests, &queue);
+
+ do {
+ struct netfs_io_subrequest *from;
+ struct iov_iter source;
+ unsigned long long start, len;
+ size_t part, deferred_next_donated = 0;
+ bool boundary = false;
+
+ /* Go through the subreqs and find the next span of contiguous
+ * buffer that we then rejig (cifs, for example, needs the
+ * rsize renegotiating) and reissue.
+ */
+ from = list_first_entry(&queue, struct netfs_io_subrequest, rreq_link);
+ list_move_tail(&from->rreq_link, &sublist);
+ start = from->start + from->transferred;
+ len = from->len - from->transferred;
+
+ _debug("from R=%08x[%x] s=%llx ctl=%zx/%zx/%zx",
+ rreq->debug_id, from->debug_index,
+ from->start, from->consumed, from->transferred, from->len);
+
+ if (test_bit(NETFS_SREQ_FAILED, &from->flags) ||
+ !test_bit(NETFS_SREQ_NEED_RETRY, &from->flags))
+ goto abandon;
+
+ deferred_next_donated = from->next_donated;
+ while ((subreq = list_first_entry_or_null(
+ &queue, struct netfs_io_subrequest, rreq_link))) {
+ if (subreq->start != start + len ||
+ subreq->transferred > 0 ||
+ !test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags))
+ break;
+ list_move_tail(&subreq->rreq_link, &sublist);
+ len += subreq->len;
+ deferred_next_donated = subreq->next_donated;
+ if (test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags))
+ break;
+ }
+
+ _debug(" - range: %llx-%llx %llx", start, start + len - 1, len);
+
+ /* Determine the set of buffers we're going to use. Each
+ * subreq gets a subset of a single overall contiguous buffer.
+ */
+ netfs_reset_iter(from);
+ source = from->io_iter;
+ source.count = len;
+
+ /* Work through the sublist. */
+ while ((subreq = list_first_entry_or_null(
+ &sublist, struct netfs_io_subrequest, rreq_link))) {
+ list_del(&subreq->rreq_link);
+
+ subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
+ subreq->start = start - subreq->transferred;
+ subreq->len = len + subreq->transferred;
+ stream0->sreq_max_len = subreq->len;
+
+ __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ __set_bit(NETFS_SREQ_RETRYING, &subreq->flags);
+
+ spin_lock_bh(&rreq->lock);
+ list_add_tail(&subreq->rreq_link, &rreq->subrequests);
+ subreq->prev_donated += rreq->prev_donated;
+ rreq->prev_donated = 0;
+ trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
+ spin_unlock_bh(&rreq->lock);
+
+ BUG_ON(!len);
+
+ /* Renegotiate max_len (rsize) */
+ if (rreq->netfs_ops->prepare_read(subreq) < 0) {
+ trace_netfs_sreq(subreq, netfs_sreq_trace_reprep_failed);
+ __set_bit(NETFS_SREQ_FAILED, &subreq->flags);
+ }
+
+ part = umin(len, stream0->sreq_max_len);
+ if (unlikely(rreq->io_streams[0].sreq_max_segs))
+ part = netfs_limit_iter(&source, 0, part, stream0->sreq_max_segs);
+ subreq->len = subreq->transferred + part;
+ subreq->io_iter = source;
+ iov_iter_truncate(&subreq->io_iter, part);
+ iov_iter_advance(&source, part);
+ len -= part;
+ start += part;
+ if (!len) {
+ if (boundary)
+ __set_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);
+ subreq->next_donated = deferred_next_donated;
+ } else {
+ __clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);
+ subreq->next_donated = 0;
+ }
+
+ netfs_reissue_read(rreq, subreq);
+ if (!len)
+ break;
+
+ /* If we ran out of subrequests, allocate another. */
+ if (list_empty(&sublist)) {
+ subreq = netfs_alloc_subrequest(rreq);
+ if (!subreq)
+ goto abandon;
+ subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
+ subreq->start = start;
+
+ /* We get two refs, but need just one. */
+ netfs_put_subrequest(subreq, false, netfs_sreq_trace_new);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_split);
+ list_add_tail(&subreq->rreq_link, &sublist);
+ }
+ }
+
+ /* If we managed to use fewer subreqs, we can discard the
+ * excess.
+ */
+ while ((subreq = list_first_entry_or_null(
+ &sublist, struct netfs_io_subrequest, rreq_link))) {
+ trace_netfs_sreq(subreq, netfs_sreq_trace_discard);
+ list_del(&subreq->rreq_link);
+ netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_done);
+ }
+
+ } while (!list_empty(&queue));
+
+ return;
+
+ /* If we hit ENOMEM, fail all remaining subrequests */
+abandon:
+ list_splice_init(&sublist, &queue);
+ list_for_each_entry(subreq, &queue, rreq_link) {
+ if (!subreq->error)
+ subreq->error = -ENOMEM;
+ __clear_bit(NETFS_SREQ_FAILED, &subreq->flags);
+ __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ __clear_bit(NETFS_SREQ_RETRYING, &subreq->flags);
+ }
+ spin_lock_bh(&rreq->lock);
+ list_splice_tail_init(&queue, &rreq->subrequests);
+ spin_unlock_bh(&rreq->lock);
+}
+
+/*
+ * Retry reads.
+ */
+void netfs_retry_reads(struct netfs_io_request *rreq)
+{
+ trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
+
+ atomic_inc(&rreq->nr_outstanding);
+
+ netfs_retry_read_subrequests(rreq);
+
+ if (atomic_dec_and_test(&rreq->nr_outstanding))
+ netfs_rreq_terminated(rreq, false);
+}
+
+/*
+ * Unlock any the pages that haven't been unlocked yet due to abandoned
+ * subrequests.
+ */
+void netfs_unlock_abandoned_read_pages(struct netfs_io_request *rreq)
+{
+ struct folio_queue *p;
+
+ for (p = rreq->buffer; p; p = p->next) {
+ for (int slot = 0; slot < folioq_count(p); slot++) {
+ struct folio *folio = folioq_folio(p, slot);
+
+ if (folio && !folioq_is_marked2(p, slot)) {
+ trace_netfs_folio(folio, netfs_folio_trace_abandon);
+ folio_unlock(folio);
+ }
+ }
+ }
+}
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index 10ff2bd290cb..43cec03c6514 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -159,10 +159,6 @@ static void netfs_prepare_write(struct netfs_io_request *wreq,

_enter("R=%x[%x]", wreq->debug_id, subreq->debug_index);

- trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index,
- refcount_read(&subreq->ref),
- netfs_sreq_trace_new);
-
trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);

stream->sreq_max_len = UINT_MAX;
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index 7202ce84d0eb..cc93cfb16f9d 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -265,6 +265,7 @@ static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *fi
{
rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
+ rreq->io_streams[0].sreq_max_len = NFS_SB(rreq->inode->i_sb)->rsize;

return 0;
}
@@ -286,14 +287,6 @@ static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sre
return netfs;
}

-static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
-{
- size_t rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
-
- sreq->len = min(sreq->len, rsize);
- return true;
-}
-
static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
{
struct nfs_netfs_io_data *netfs;
@@ -302,17 +295,18 @@ static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
struct page *page;
unsigned long idx;
+ pgoff_t start, last;
int err;
- pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
- pgoff_t last = ((sreq->start + sreq->len -
- sreq->transferred - 1) >> PAGE_SHIFT);
+
+ start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
+ last = ((sreq->start + sreq->len - sreq->transferred - 1) >> PAGE_SHIFT);

nfs_pageio_init_read(&pgio, inode, false,
&nfs_async_read_completion_ops);

netfs = nfs_netfs_alloc(sreq);
if (!netfs)
- return netfs_subreq_terminated(sreq, -ENOMEM, false);
+ return netfs_read_subreq_terminated(sreq, -ENOMEM, false);

pgio.pg_netfs = netfs; /* used in completion */

@@ -377,5 +371,4 @@ const struct netfs_request_ops nfs_netfs_ops = {
.init_request = nfs_netfs_init_request,
.free_request = nfs_netfs_free_request,
.issue_read = nfs_netfs_issue_read,
- .clamp_length = nfs_netfs_clamp_length
};
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index fbed0027996f..5edebcff8ddf 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -60,8 +60,6 @@ static inline void nfs_netfs_get(struct nfs_netfs_io_data *netfs)

static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
{
- ssize_t final_len;
-
/* Only the last RPC completion should call netfs_subreq_terminated() */
if (!refcount_dec_and_test(&netfs->refcount))
return;
@@ -74,8 +72,9 @@ static inline void nfs_netfs_put(struct nfs_netfs_io_data *netfs)
* Correct the final length here to be no larger than the netfs subrequest
* length, and thus avoid netfs's "Subreq overread" warning message.
*/
- final_len = min_t(s64, netfs->sreq->len, atomic64_read(&netfs->transferred));
- netfs_subreq_terminated(netfs->sreq, netfs->error ?: final_len, false);
+ netfs->sreq->transferred = min_t(s64, netfs->sreq->len,
+ atomic64_read(&netfs->transferred));
+ netfs_read_subreq_terminated(netfs->sreq, netfs->error, false);
kfree(netfs);
}
static inline void nfs_netfs_inode_init(struct nfs_inode *nfsi)
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index 595c4b673707..d5e1bbefd5e8 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -1309,10 +1309,8 @@ cifs_readv_callback(struct mid_q_entry *mid)
if (rdata->result == 0 || rdata->result == -EAGAIN)
iov_iter_advance(&rdata->subreq.io_iter, rdata->got_bytes);
rdata->credits.value = 0;
- netfs_subreq_terminated(&rdata->subreq,
- (rdata->result == 0 || rdata->result == -EAGAIN) ?
- rdata->got_bytes : rdata->result,
- false);
+ rdata->subreq.transferred += rdata->got_bytes;
+ netfs_read_subreq_terminated(&rdata->subreq, rdata->result, false);
release_mid(mid);
add_credits(server, &credits, 0);
}
diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index c1d8c5d2ac71..569c17b41b8e 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -140,25 +140,22 @@ static void cifs_netfs_invalidate_cache(struct netfs_io_request *wreq)
}

/*
- * Split the read up according to how many credits we can get for each piece.
- * It's okay to sleep here if we need to wait for more credit to become
- * available.
- *
- * We also choose the server and allocate an operation ID to be cleaned up
- * later.
+ * Negotiate the size of a read operation on behalf of the netfs library.
*/
-static bool cifs_clamp_length(struct netfs_io_subrequest *subreq)
+static int cifs_prepare_read(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *rreq = subreq->rreq;
- struct netfs_io_stream *stream = &rreq->io_streams[subreq->stream_nr];
struct cifs_io_subrequest *rdata = container_of(subreq, struct cifs_io_subrequest, subreq);
struct cifs_io_request *req = container_of(subreq->rreq, struct cifs_io_request, rreq);
struct TCP_Server_Info *server = req->server;
struct cifs_sb_info *cifs_sb = CIFS_SB(rreq->inode->i_sb);
- int rc;
+ size_t size;
+ int rc = 0;

- rdata->xid = get_xid();
- rdata->have_xid = true;
+ if (!rdata->have_xid) {
+ rdata->xid = get_xid();
+ rdata->have_xid = true;
+ }
rdata->server = server;

if (cifs_sb->ctx->rsize == 0)
@@ -166,13 +163,12 @@ static bool cifs_clamp_length(struct netfs_io_subrequest *subreq)
server->ops->negotiate_rsize(tlink_tcon(req->cfile->tlink),
cifs_sb->ctx);

-
rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->rsize,
- &stream->sreq_max_len, &rdata->credits);
- if (rc) {
- subreq->error = rc;
- return false;
- }
+ &size, &rdata->credits);
+ if (rc)
+ return rc;
+
+ rreq->io_streams[0].sreq_max_len = size;

rdata->credits.in_flight_check = 1;
rdata->credits.rreq_debug_id = rreq->debug_id;
@@ -184,13 +180,11 @@ static bool cifs_clamp_length(struct netfs_io_subrequest *subreq)
server->credits, server->in_flight, 0,
cifs_trace_rw_credits_read_submit);

- subreq->len = umin(subreq->len, stream->sreq_max_len);
-
#ifdef CONFIG_CIFS_SMB_DIRECT
if (server->smbd_conn)
- stream->sreq_max_segs = server->smbd_conn->max_frmr_depth;
+ rreq->io_streams[0].sreq_max_segs = server->smbd_conn->max_frmr_depth;
#endif
- return true;
+ return 0;
}

/*
@@ -199,31 +193,40 @@ static bool cifs_clamp_length(struct netfs_io_subrequest *subreq)
* to only read a portion of that, but as long as we read something, the netfs
* helper will call us again so that we can issue another read.
*/
-static void cifs_req_issue_read(struct netfs_io_subrequest *subreq)
+static void cifs_issue_read(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *rreq = subreq->rreq;
struct cifs_io_subrequest *rdata = container_of(subreq, struct cifs_io_subrequest, subreq);
struct cifs_io_request *req = container_of(subreq->rreq, struct cifs_io_request, rreq);
+ struct TCP_Server_Info *server = req->server;
int rc = 0;

cifs_dbg(FYI, "%s: op=%08x[%x] mapping=%p len=%zu/%zu\n",
__func__, rreq->debug_id, subreq->debug_index, rreq->mapping,
subreq->transferred, subreq->len);

+ rc = adjust_credits(server, rdata, cifs_trace_rw_credits_issue_read_adjust);
+ if (rc)
+ goto failed;
+
if (req->cfile->invalidHandle) {
do {
rc = cifs_reopen_file(req->cfile, true);
} while (rc == -EAGAIN);
if (rc)
- goto out;
+ goto failed;
}

__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);

+ trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
rc = rdata->server->ops->async_readv(rdata);
-out:
if (rc)
- netfs_subreq_terminated(subreq, rc, false);
+ goto failed;
+ return;
+
+failed:
+ netfs_read_subreq_terminated(subreq, rc, false);
}

/*
@@ -330,8 +333,8 @@ const struct netfs_request_ops cifs_req_ops = {
.init_request = cifs_init_request,
.free_request = cifs_free_request,
.free_subrequest = cifs_free_subrequest,
- .clamp_length = cifs_clamp_length,
- .issue_read = cifs_req_issue_read,
+ .prepare_read = cifs_prepare_read,
+ .issue_read = cifs_issue_read,
.done = cifs_rreq_done,
.begin_writeback = cifs_begin_writeback,
.prepare_write = cifs_prepare_write,
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index 9a06b5594669..dbc9e69ad223 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -4495,9 +4495,7 @@ static void smb2_readv_worker(struct work_struct *work)
struct cifs_io_subrequest *rdata =
container_of(work, struct cifs_io_subrequest, subreq.work);

- netfs_subreq_terminated(&rdata->subreq,
- (rdata->result == 0 || rdata->result == -EAGAIN) ?
- rdata->got_bytes : rdata->result, true);
+ netfs_read_subreq_terminated(&rdata->subreq, rdata->result, false);
}

static void
@@ -4551,6 +4549,7 @@ smb2_readv_callback(struct mid_q_entry *mid)
break;
case MID_REQUEST_SUBMITTED:
case MID_RETRY_NEEDED:
+ __set_bit(NETFS_SREQ_NEED_RETRY, &rdata->subreq.flags);
rdata->result = -EAGAIN;
if (server->sign && rdata->got_bytes)
/* reset bytes number since we can not check a sign */
@@ -4604,6 +4603,10 @@ smb2_readv_callback(struct mid_q_entry *mid)
server->credits, server->in_flight,
0, cifs_trace_rw_credits_read_response_clear);
rdata->credits.value = 0;
+ rdata->subreq.transferred += rdata->got_bytes;
+ if (rdata->subreq.start + rdata->subreq.transferred >= rdata->subreq.rreq->i_size)
+ __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags);
+ trace_netfs_sreq(&rdata->subreq, netfs_sreq_trace_io_progress);
INIT_WORK(&rdata->subreq.work, smb2_readv_worker);
queue_work(cifsiod_wq, &rdata->subreq.work);
release_mid(mid);
@@ -4867,6 +4870,7 @@ smb2_writev_callback(struct mid_q_entry *mid)
server->credits, server->in_flight,
0, cifs_trace_rw_credits_write_response_clear);
wdata->credits.value = 0;
+ trace_netfs_sreq(&wdata->subreq, netfs_sreq_trace_io_progress);
cifs_write_subrequest_terminated(wdata, result ?: written, true);
release_mid(mid);
trace_smb3_rw_credits(rreq_debug_id, subreq_debug_index, 0,
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index c47753a24623..be1686f0fe34 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -180,20 +180,26 @@ struct netfs_io_subrequest {
unsigned long long start; /* Where to start the I/O */
size_t len; /* Size of the I/O */
size_t transferred; /* Amount of data transferred */
+ size_t consumed; /* Amount of read data consumed */
+ size_t prev_donated; /* Amount of data donated from previous subreq */
+ size_t next_donated; /* Amount of data donated from next subreq */
refcount_t ref;
short error; /* 0 or error that occurred */
unsigned short debug_index; /* Index in list (for debugging output) */
unsigned int nr_segs; /* Number of segs in io_iter */
enum netfs_io_source source; /* Where to read from/write to */
unsigned char stream_nr; /* I/O stream this belongs to */
+ unsigned char curr_folioq_slot; /* Folio currently being read */
+ unsigned char curr_folio_order; /* Order of folio */
+ struct folio_queue *curr_folioq; /* Queue segment in which current folio resides */
unsigned long flags;
#define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
-#define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */
#define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
#define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
#define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
#define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */
+#define NETFS_SREQ_HIT_EOF 7 /* Set if short due to EOF */
#define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */
#define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */
#define NETFS_SREQ_RETRYING 10 /* Set if we're retrying */
@@ -203,6 +209,7 @@ struct netfs_io_subrequest {
enum netfs_io_origin {
NETFS_READAHEAD, /* This read was triggered by readahead */
NETFS_READPAGE, /* This read is a synchronous read */
+ NETFS_READ_GAPS, /* This read is a synchronous read to fill gaps */
NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
NETFS_DIO_READ, /* This is a direct I/O read */
NETFS_WRITEBACK, /* This write was triggered by writepages */
@@ -225,6 +232,7 @@ struct netfs_io_request {
struct address_space *mapping; /* The mapping being accessed */
struct kiocb *iocb; /* AIO completion vector */
struct netfs_cache_resources cache_resources;
+ struct readahead_control *ractl; /* Readahead descriptor */
struct list_head proc_link; /* Link in netfs_iorequests */
struct list_head subrequests; /* Contributory I/O operations */
struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */
@@ -245,12 +253,10 @@ struct netfs_io_request {
unsigned int nr_group_rel; /* Number of refs to release on ->group */
spinlock_t lock; /* Lock for queuing subreqs */
atomic_t nr_outstanding; /* Number of ops in progress */
- atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */
- size_t upper_len; /* Length can be extended to here */
unsigned long long submitted; /* Amount submitted for I/O so far */
unsigned long long len; /* Length of the request */
size_t transferred; /* Amount to be indicated as transferred */
- short error; /* 0 or error that occurred */
+ long error; /* 0 or error that occurred */
enum netfs_io_origin origin; /* Origin of the request */
bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
u8 buffer_head_slot; /* First slot in ->buffer */
@@ -261,9 +267,9 @@ struct netfs_io_request {
unsigned long long collected_to; /* Point we've collected to */
unsigned long long cleaned_to; /* Position we've cleaned folios to */
pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
+ size_t prev_donated; /* Fallback for subreq->prev_donated */
refcount_t ref;
unsigned long flags;
-#define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
#define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
#define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
#define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
@@ -276,6 +282,7 @@ struct netfs_io_request {
#define NETFS_RREQ_PAUSE 11 /* Pause subrequest generation */
#define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */
#define NETFS_RREQ_ALL_QUEUED 13 /* All subreqs are now queued */
+#define NETFS_RREQ_NEED_RETRY 14 /* Need to try retrying */
#define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
* write to cache on read */
const struct netfs_request_ops *netfs_ops;
@@ -294,7 +301,7 @@ struct netfs_request_ops {

/* Read request handling */
void (*expand_readahead)(struct netfs_io_request *rreq);
- bool (*clamp_length)(struct netfs_io_subrequest *subreq);
+ int (*prepare_read)(struct netfs_io_subrequest *subreq);
void (*issue_read)(struct netfs_io_subrequest *subreq);
bool (*is_still_valid)(struct netfs_io_request *rreq);
int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
@@ -424,7 +431,10 @@ bool netfs_release_folio(struct folio *folio, gfp_t gfp);
vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);

/* (Sub)request management API. */
-void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);
+void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq,
+ bool was_async);
+void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
+ int error, bool was_async);
void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
enum netfs_sreq_ref_trace what);
void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 065fa168f964..4ac3b5d56ebd 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -20,6 +20,7 @@
EM(netfs_read_trace_expanded, "EXPANDED ") \
EM(netfs_read_trace_readahead, "READAHEAD") \
EM(netfs_read_trace_readpage, "READPAGE ") \
+ EM(netfs_read_trace_read_gaps, "READ-GAPS") \
EM(netfs_read_trace_prefetch_for_write, "PREFETCHW") \
E_(netfs_read_trace_write_begin, "WRITEBEGN")

@@ -33,6 +34,7 @@
#define netfs_rreq_origins \
EM(NETFS_READAHEAD, "RA") \
EM(NETFS_READPAGE, "RP") \
+ EM(NETFS_READ_GAPS, "RG") \
EM(NETFS_READ_FOR_WRITE, "RW") \
EM(NETFS_DIO_READ, "DR") \
EM(NETFS_WRITEBACK, "WB") \
@@ -68,15 +70,25 @@
E_(NETFS_INVALID_WRITE, "INVL")

#define netfs_sreq_traces \
+ EM(netfs_sreq_trace_add_donations, "+DON ") \
+ EM(netfs_sreq_trace_added, "ADD ") \
+ EM(netfs_sreq_trace_clear, "CLEAR") \
EM(netfs_sreq_trace_discard, "DSCRD") \
+ EM(netfs_sreq_trace_donate_to_prev, "DON-P") \
+ EM(netfs_sreq_trace_donate_to_next, "DON-N") \
EM(netfs_sreq_trace_download_instead, "RDOWN") \
EM(netfs_sreq_trace_fail, "FAIL ") \
EM(netfs_sreq_trace_free, "FREE ") \
+ EM(netfs_sreq_trace_hit_eof, "EOF ") \
+ EM(netfs_sreq_trace_io_progress, "IO ") \
EM(netfs_sreq_trace_limited, "LIMIT") \
EM(netfs_sreq_trace_prepare, "PREP ") \
EM(netfs_sreq_trace_prep_failed, "PRPFL") \
- EM(netfs_sreq_trace_resubmit_short, "SHORT") \
+ EM(netfs_sreq_trace_progress, "PRGRS") \
+ EM(netfs_sreq_trace_reprep_failed, "REPFL") \
EM(netfs_sreq_trace_retry, "RETRY") \
+ EM(netfs_sreq_trace_short, "SHORT") \
+ EM(netfs_sreq_trace_split, "SPLIT") \
EM(netfs_sreq_trace_submit, "SUBMT") \
EM(netfs_sreq_trace_terminated, "TERM ") \
EM(netfs_sreq_trace_write, "WRITE") \
@@ -117,7 +129,7 @@
EM(netfs_sreq_trace_new, "NEW ") \
EM(netfs_sreq_trace_put_cancel, "PUT CANCEL ") \
EM(netfs_sreq_trace_put_clear, "PUT CLEAR ") \
- EM(netfs_sreq_trace_put_discard, "PUT DISCARD") \
+ EM(netfs_sreq_trace_put_consumed, "PUT CONSUME") \
EM(netfs_sreq_trace_put_done, "PUT DONE ") \
EM(netfs_sreq_trace_put_failed, "PUT FAILED ") \
EM(netfs_sreq_trace_put_merged, "PUT MERGED ") \
@@ -137,6 +149,7 @@
EM(netfs_flush_content, "flush") \
EM(netfs_streaming_filled_page, "mod-streamw-f") \
EM(netfs_streaming_cont_filled_page, "mod-streamw-f+") \
+ EM(netfs_folio_trace_abandon, "abandon") \
EM(netfs_folio_trace_cancel_copy, "cancel-copy") \
EM(netfs_folio_trace_clear, "clear") \
EM(netfs_folio_trace_clear_cc, "clear-cc") \
@@ -152,7 +165,10 @@
EM(netfs_folio_trace_mkwrite_plus, "mkwrite+") \
EM(netfs_folio_trace_not_under_wback, "!wback") \
EM(netfs_folio_trace_put, "put") \
+ EM(netfs_folio_trace_read, "read") \
+ EM(netfs_folio_trace_read_done, "read-done") \
EM(netfs_folio_trace_read_gaps, "read-gaps") \
+ EM(netfs_folio_trace_read_put, "read-put") \
EM(netfs_folio_trace_redirtied, "redirtied") \
EM(netfs_folio_trace_store, "store") \
EM(netfs_folio_trace_store_copy, "store-copy") \
@@ -165,6 +181,12 @@
EM(netfs_contig_trace_jump, "-->JUMP-->") \
E_(netfs_contig_trace_unlock, "Unlock")

+#define netfs_donate_traces \
+ EM(netfs_trace_donate_tail_to_prev, "tail-to-prev") \
+ EM(netfs_trace_donate_to_prev, "to-prev") \
+ EM(netfs_trace_donate_to_next, "to-next") \
+ E_(netfs_trace_donate_to_deferred_next, "defer-next")
+
#ifndef __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
#define __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY

@@ -182,6 +204,7 @@ enum netfs_rreq_ref_trace { netfs_rreq_ref_traces } __mode(byte);
enum netfs_sreq_ref_trace { netfs_sreq_ref_traces } __mode(byte);
enum netfs_folio_trace { netfs_folio_traces } __mode(byte);
enum netfs_collect_contig_trace { netfs_collect_contig_traces } __mode(byte);
+enum netfs_donate_trace { netfs_donate_traces } __mode(byte);

#endif

@@ -204,6 +227,7 @@ netfs_rreq_ref_traces;
netfs_sreq_ref_traces;
netfs_folio_traces;
netfs_collect_contig_traces;
+netfs_donate_traces;

/*
* Now redefine the EM() and E_() macros to map the enums to the strings that
@@ -224,6 +248,7 @@ TRACE_EVENT(netfs_read,
TP_STRUCT__entry(
__field(unsigned int, rreq )
__field(unsigned int, cookie )
+ __field(loff_t, i_size )
__field(loff_t, start )
__field(size_t, len )
__field(enum netfs_read_trace, what )
@@ -233,18 +258,19 @@ TRACE_EVENT(netfs_read,
TP_fast_assign(
__entry->rreq = rreq->debug_id;
__entry->cookie = rreq->cache_resources.debug_id;
+ __entry->i_size = rreq->i_size;
__entry->start = start;
__entry->len = len;
__entry->what = what;
__entry->netfs_inode = rreq->inode->i_ino;
),

- TP_printk("R=%08x %s c=%08x ni=%x s=%llx %zx",
+ TP_printk("R=%08x %s c=%08x ni=%x s=%llx l=%zx sz=%llx",
__entry->rreq,
__print_symbolic(__entry->what, netfs_read_traces),
__entry->cookie,
__entry->netfs_inode,
- __entry->start, __entry->len)
+ __entry->start, __entry->len, __entry->i_size)
);

TRACE_EVENT(netfs_rreq,
@@ -649,6 +675,71 @@ TRACE_EVENT(netfs_collect_stream,
__entry->collected_to, __entry->front)
);

+TRACE_EVENT(netfs_progress,
+ TP_PROTO(const struct netfs_io_subrequest *subreq,
+ unsigned long long start, size_t avail, size_t part),
+
+ TP_ARGS(subreq, start, avail, part),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, rreq)
+ __field(unsigned int, subreq)
+ __field(unsigned int, consumed)
+ __field(unsigned int, transferred)
+ __field(unsigned long long, f_start)
+ __field(unsigned int, f_avail)
+ __field(unsigned int, f_part)
+ __field(unsigned char, slot)
+ ),
+
+ TP_fast_assign(
+ __entry->rreq = subreq->rreq->debug_id;
+ __entry->subreq = subreq->debug_index;
+ __entry->consumed = subreq->consumed;
+ __entry->transferred = subreq->transferred;
+ __entry->f_start = start;
+ __entry->f_avail = avail;
+ __entry->f_part = part;
+ __entry->slot = subreq->curr_folioq_slot;
+ ),
+
+ TP_printk("R=%08x[%02x] s=%llx ct=%x/%x pa=%x/%x sl=%x",
+ __entry->rreq, __entry->subreq, __entry->f_start,
+ __entry->consumed, __entry->transferred,
+ __entry->f_part, __entry->f_avail, __entry->slot)
+ );
+
+TRACE_EVENT(netfs_donate,
+ TP_PROTO(const struct netfs_io_request *rreq,
+ const struct netfs_io_subrequest *from,
+ const struct netfs_io_subrequest *to,
+ size_t amount,
+ enum netfs_donate_trace trace),
+
+ TP_ARGS(rreq, from, to, amount, trace),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, rreq)
+ __field(unsigned int, from)
+ __field(unsigned int, to)
+ __field(unsigned int, amount)
+ __field(enum netfs_donate_trace, trace)
+ ),
+
+ TP_fast_assign(
+ __entry->rreq = rreq->debug_id;
+ __entry->from = from->debug_index;
+ __entry->to = to ? to->debug_index : -1;
+ __entry->amount = amount;
+ __entry->trace = trace;
+ ),
+
+ TP_printk("R=%08x[%02x] -> [%02x] %s am=%x",
+ __entry->rreq, __entry->from, __entry->to,
+ __print_symbolic(__entry->trace, netfs_donate_traces),
+ __entry->amount)
+ );
+
#undef EM
#undef E_
#endif /* _TRACE_NETFS_H */