From: David Howells <dhowells@redhat.com>
To: Jeff Layton <jlayton@kernel.org>, Steve French <smfrench@gmail.com>
Cc: David Howells <dhowells@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Marc Dionne <marc.dionne@auristor.com>,
Paulo Alcantara <pc@manguebit.com>,
Shyam Prasad N <sprasad@microsoft.com>,
Tom Talpey <tom@talpey.com>,
Dominique Martinet <asmadeus@codewreck.org>,
Eric Van Hensbergen <ericvh@kernel.org>,
Ilya Dryomov <idryomov@gmail.com>,
Christian Brauner <christian@brauner.io>,
linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org,
ceph-devel@vger.kernel.org, v9fs@lists.linux.dev,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v5 26/40] netfs: Make netfs_read_folio() handle streaming-write pages
Date: Thu, 21 Dec 2023 13:23:21 +0000 [thread overview]
Message-ID: <20231221132400.1601991-27-dhowells@redhat.com> (raw)
In-Reply-To: <20231221132400.1601991-1-dhowells@redhat.com>
netfs_read_folio() needs to handle partially-valid pages that are marked
dirty, but not uptodate in the event that someone tries to read a page was
used to cache data by a streaming write.
In such a case, make netfs_read_folio() set up a bvec iterator that points
to the parts of the folio that need filling and to a sink page for the data
that should be discarded and use that instead of i_pages as the iterator to
be written to.
This requires netfs_rreq_unlock_folios() to convert the page into a normal
dirty uptodate page, getting rid of the partial write record and bumping
the group pointer over to folio->private.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
---
fs/netfs/buffered_read.c | 61 ++++++++++++++++++++++++++++++++++--
include/trace/events/netfs.h | 2 ++
2 files changed, 60 insertions(+), 3 deletions(-)
diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index 73a6e4d61f9d..950f63fc156a 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -16,6 +16,7 @@
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;
@@ -87,6 +88,15 @@ void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
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);
}
@@ -239,6 +249,7 @@ int netfs_read_folio(struct file *file, struct folio *folio)
struct address_space *mapping = folio_file_mapping(folio);
struct netfs_io_request *rreq;
struct netfs_inode *ctx = netfs_inode(mapping->host);
+ struct folio *sink = NULL;
int ret;
_enter("%lx", folio_index(folio));
@@ -259,12 +270,56 @@ 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 */
- iov_iter_xarray(&rreq->iter, ITER_DEST, &mapping->i_pages,
- rreq->start, rreq->len);
+ 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_begin_read(rreq, true);
+ if (sink)
+ folio_put(sink);
netfs_put_request(rreq, false, netfs_rreq_trace_put_return);
- return ret;
+ return ret < 0 ? ret : 0;
discard:
netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 8308b81f36be..082a5e717b58 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -118,9 +118,11 @@
EM(netfs_folio_trace_clear_g, "clear-g") \
EM(netfs_folio_trace_copy_to_cache, "copy") \
EM(netfs_folio_trace_end_copy, "end-copy") \
+ EM(netfs_folio_trace_filled_gaps, "filled-gaps") \
EM(netfs_folio_trace_kill, "kill") \
EM(netfs_folio_trace_mkwrite, "mkwrite") \
EM(netfs_folio_trace_mkwrite_plus, "mkwrite+") \
+ EM(netfs_folio_trace_read_gaps, "read-gaps") \
EM(netfs_folio_trace_redirty, "redirty") \
EM(netfs_folio_trace_redirtied, "redirtied") \
EM(netfs_folio_trace_store, "store") \
next prev parent reply other threads:[~2023-12-21 13:25 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-21 13:22 [PATCH v5 00/40] netfs, afs, 9p: Delegate high-level I/O to netfslib David Howells
2023-12-21 13:22 ` [PATCH v5 01/40] afs: Remove whitespace before most ')' from the trace header David Howells
2023-12-21 13:22 ` [PATCH v5 02/40] afs: Automatically generate trace tag enums David Howells
2023-12-21 13:22 ` [PATCH v5 03/40] netfs, fscache: Move fs/fscache/* into fs/netfs/ David Howells
2023-12-21 13:22 ` [PATCH v5 04/40] netfs, fscache: Combine fscache with netfs David Howells
2023-12-21 13:23 ` [PATCH v5 05/40] netfs, fscache: Remove ->begin_cache_operation David Howells
2023-12-21 13:23 ` [PATCH v5 06/40] netfs, fscache: Move /proc/fs/fscache to /proc/fs/netfs and put in a symlink David Howells
2024-01-03 16:49 ` Marc Dionne
2023-12-21 13:23 ` [PATCH v5 07/40] netfs: Move pinning-for-writeback from fscache to netfs David Howells
2023-12-21 13:23 ` [PATCH v5 08/40] netfs: Add a procfile to list in-progress requests David Howells
2023-12-21 13:23 ` [PATCH v5 09/40] netfs: Allow the netfs to make the io (sub)request alloc larger David Howells
2023-12-21 13:23 ` [PATCH v5 10/40] netfs: Add a ->free_subrequest() op David Howells
2023-12-21 13:23 ` [PATCH v5 11/40] afs: Don't use folio->private to record partial modification David Howells
2023-12-21 13:23 ` [PATCH v5 12/40] netfs: Provide invalidate_folio and release_folio calls David Howells
2023-12-21 13:23 ` [PATCH v5 13/40] netfs: Implement unbuffered/DIO vs buffered I/O locking David Howells
2023-12-21 13:23 ` [PATCH v5 14/40] netfs: Add iov_iters to (sub)requests to describe various buffers David Howells
2023-12-21 13:23 ` [PATCH v5 15/40] netfs: Add support for DIO buffering David Howells
2023-12-26 16:54 ` Nathan Chancellor
2023-12-28 10:47 ` Christian Brauner
2023-12-28 16:58 ` Nathan Chancellor
2023-12-21 13:23 ` [PATCH v5 16/40] netfs: Provide tools to create a buffer in an xarray David Howells
2023-12-21 13:23 ` [PATCH v5 17/40] netfs: Add func to calculate pagecount/size-limited span of an iterator David Howells
2023-12-21 13:23 ` [PATCH v5 18/40] netfs: Limit subrequest by size or number of segments David Howells
2023-12-21 13:23 ` [PATCH v5 19/40] netfs: Extend the netfs_io_*request structs to handle writes David Howells
2023-12-21 13:23 ` [PATCH v5 20/40] netfs: Add a hook to allow tell the netfs to update its i_size David Howells
2023-12-21 13:23 ` [PATCH v5 21/40] netfs: Make netfs_put_request() handle a NULL pointer David Howells
2023-12-21 13:23 ` [PATCH v5 22/40] netfs: Make the refcounting of netfs_begin_read() easier to use David Howells
2023-12-21 13:23 ` [PATCH v5 23/40] netfs: Prep to use folio->private for write grouping and streaming write David Howells
2023-12-21 13:23 ` [PATCH v5 24/40] netfs: Dispatch write requests to process a writeback slice David Howells
2023-12-21 13:23 ` [PATCH v5 25/40] netfs: Provide func to copy data to pagecache for buffered write David Howells
2023-12-21 13:23 ` David Howells [this message]
2023-12-21 13:23 ` [PATCH v5 27/40] netfs: Allocate multipage folios in the writepath David Howells
2023-12-21 13:23 ` [PATCH v5 28/40] netfs: Implement unbuffered/DIO read support David Howells
2023-12-21 13:23 ` [PATCH v5 29/40] netfs: Implement unbuffered/DIO write support David Howells
2023-12-21 13:23 ` [PATCH v5 30/40] netfs: Implement buffered write API David Howells
2023-12-21 13:23 ` [PATCH v5 31/40] netfs: Allow buffered shared-writeable mmap through netfs_page_mkwrite() David Howells
2023-12-21 13:23 ` [PATCH v5 32/40] netfs: Provide netfs_file_read_iter() David Howells
2023-12-21 13:23 ` [PATCH v5 33/40] netfs, cachefiles: Pass upper bound length to allow expansion David Howells
2024-01-02 14:04 ` Gao Xiang
2024-01-02 17:11 ` David Howells
2024-01-02 20:37 ` Gao Xiang
2024-01-03 10:15 ` Jia Zhu
2023-12-21 13:23 ` [PATCH v5 34/40] netfs: Provide a writepages implementation David Howells
2023-12-21 13:23 ` [PATCH v5 35/40] netfs: Provide a launder_folio implementation David Howells
2023-12-21 13:23 ` [PATCH v5 36/40] netfs: Implement a write-through caching option David Howells
2023-12-21 13:23 ` [PATCH v5 37/40] netfs: Optimise away reads above the point at which there can be no data David Howells
2023-12-21 23:01 ` Nathan Chancellor
2023-12-22 11:49 ` David Howells
2023-12-22 12:00 ` [PATCH] Fix oops in NFS David Howells
2024-01-05 4:52 ` Matthew Wilcox
2024-01-05 10:12 ` David Howells
2024-01-05 13:17 ` Matthew Wilcox
2024-01-05 17:20 ` Dominique Martinet
2024-01-05 11:48 ` David Howells
2024-01-05 14:33 ` David Howells
2023-12-21 13:23 ` [PATCH v5 38/40] netfs: Export the netfs_sreq tracepoint David Howells
2023-12-21 13:23 ` [PATCH v5 39/40] afs: Use the netfs write helpers David Howells
2023-12-21 13:23 ` [PATCH v5 40/40] 9p: Use netfslib read/write_iter David Howells
2024-01-03 7:22 ` Dominique Martinet
2024-01-03 19:52 ` Eric Van Hensbergen
2024-01-03 12:08 ` David Howells
2024-01-03 12:39 ` David Howells
2024-01-03 13:00 ` Dominique Martinet
2024-05-09 17:15 ` Andrea Righi
2024-05-09 21:33 ` David Howells
2024-05-10 5:53 ` Andrea Righi
2024-05-10 7:57 ` David Howells
2023-12-22 13:02 ` [PATCH] Fix EROFS Kconfig David Howells
2023-12-23 3:55 ` Jingbo Xu
2023-12-23 13:32 ` Gao Xiang
2024-01-02 15:39 ` [PATCH v5 40/40] 9p: Use netfslib read/write_iter David Howells
2024-01-02 21:49 ` [PATCH] 9p: Fix initialisation of netfs_inode for 9p David Howells
2024-01-03 13:10 ` Dominique Martinet
2024-01-03 13:59 ` David Howells
2024-01-03 14:04 ` David Howells
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