[PATCH v3 41/59] netfs: Provide a launder_folio implementation

David Howells
2023-12-07T21:24:48Z

Provide a launder_folio implementation for netfslib.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
---
fs/netfs/buffered_write.c | 74 ++++++++++++++++++++++++++++++++++++
fs/netfs/main.c | 1 +
include/linux/netfs.h | 2 +
include/trace/events/netfs.h | 3 ++
4 files changed, 80 insertions(+)

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index bffa508945cb..a71a9af1b880 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -1124,3 +1124,77 @@ int netfs_writepages(struct address_space *mapping,
return ret;
}
EXPORT_SYMBOL(netfs_writepages);
+
+/*
+ * Deal with the disposition of a laundered folio.
+ */
+static void netfs_cleanup_launder_folio(struct netfs_io_request *wreq)
+{
+ if (wreq->error) {
+ pr_notice("R=%08x Laundering error %d\n", wreq->debug_id, wreq->error);
+ mapping_set_error(wreq->mapping, wreq->error);
+ }
+}
+
+/**
+ * netfs_launder_folio - Clean up a dirty folio that's being invalidated
+ * @folio: The folio to clean
+ *
+ * This is called to write back a folio that's being invalidated when an inode
+ * is getting torn down. Ideally, writepages would be used instead.
+ */
+int netfs_launder_folio(struct folio *folio)
+{
+ struct netfs_io_request *wreq;
+ struct address_space *mapping = folio->mapping;
+ struct netfs_folio *finfo = netfs_folio_info(folio);
+ struct netfs_group *group = netfs_folio_group(folio);
+ struct bio_vec bvec;
+ unsigned long long i_size = i_size_read(mapping->host);
+ unsigned long long start = folio_pos(folio);
+ size_t offset = 0, len;
+ int ret = 0;
+
+ if (finfo) {
+ offset = finfo->dirty_offset;
+ start += offset;
+ len = finfo->dirty_len;
+ } else {
+ len = folio_size(folio);
+ }
+ len = min_t(unsigned long long, len, i_size - start);
+
+ wreq = netfs_alloc_request(mapping, NULL, start, len, NETFS_LAUNDER_WRITE);
+ if (IS_ERR(wreq)) {
+ ret = PTR_ERR(wreq);
+ goto out;
+ }
+
+ if (!folio_clear_dirty_for_io(folio))
+ goto out_put;
+
+ trace_netfs_folio(folio, netfs_folio_trace_launder);
+
+ _debug("launder %llx-%llx", start, start + len - 1);
+
+ /* Speculatively write to the cache. We have to fix this up later if
+ * the store fails.
+ */
+ wreq->cleanup = netfs_cleanup_launder_folio;
+
+ bvec_set_folio(&bvec, folio, len, offset);
+ iov_iter_bvec(&wreq->iter, ITER_SOURCE, &bvec, 1, len);
+ __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
+ ret = netfs_begin_write(wreq, true, netfs_write_trace_launder);
+
+out_put:
+ folio_detach_private(folio);
+ netfs_put_group(group);
+ kfree(finfo);
+ netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
+out:
+ folio_wait_fscache(folio);
+ _leave(" = %d", ret);
+ return ret;
+}
+EXPORT_SYMBOL(netfs_launder_folio);
diff --git a/fs/netfs/main.c b/fs/netfs/main.c
index 122264d5c254..1e43bc73e130 100644
--- a/fs/netfs/main.c
+++ b/fs/netfs/main.c
@@ -33,6 +33,7 @@ static const char *netfs_origins[nr__netfs_io_origin] = {
[NETFS_READPAGE] = "RP",
[NETFS_READ_FOR_WRITE] = "RW",
[NETFS_WRITEBACK] = "WB",
+ [NETFS_LAUNDER_WRITE] = "LW",
[NETFS_RMW_READ] = "RM",
[NETFS_UNBUFFERED_WRITE] = "UW",
[NETFS_DIO_READ] = "DR",
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index a9898c99e2ba..5ceb03abf1ff 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -232,6 +232,7 @@ enum netfs_io_origin {
NETFS_READPAGE, /* This read is a synchronous read */
NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
NETFS_WRITEBACK, /* This write was triggered by writepages */
+ NETFS_LAUNDER_WRITE, /* This is triggered by ->launder_folio() */
NETFS_RMW_READ, /* This is an unbuffered read for RMW */
NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */
NETFS_DIO_READ, /* This is a direct I/O read */
@@ -424,6 +425,7 @@ int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
bool netfs_release_folio(struct folio *folio, gfp_t gfp);
+int netfs_launder_folio(struct folio *folio);

/* VMA operations API. */
vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 4dc5fcc7b0a4..94669fad4b7a 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -25,6 +25,7 @@

#define netfs_write_traces \
EM(netfs_write_trace_dio_write, "DIO-WRITE") \
+ EM(netfs_write_trace_launder, "LAUNDER ") \
EM(netfs_write_trace_unbuffered_write, "UNB-WRITE") \
E_(netfs_write_trace_writeback, "WRITEBACK")

@@ -33,6 +34,7 @@
EM(NETFS_READPAGE, "RP") \
EM(NETFS_READ_FOR_WRITE, "RW") \
EM(NETFS_WRITEBACK, "WB") \
+ EM(NETFS_LAUNDER_WRITE, "LW") \
EM(NETFS_RMW_READ, "RM") \
EM(NETFS_UNBUFFERED_WRITE, "UW") \
EM(NETFS_DIO_READ, "DR") \
@@ -132,6 +134,7 @@
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_launder, "launder") \
EM(netfs_folio_trace_mkwrite, "mkwrite") \
EM(netfs_folio_trace_mkwrite_plus, "mkwrite+") \
EM(netfs_folio_trace_read_gaps, "read-gaps") \