diff options
| author | David Howells <dhowells@redhat.com> | 2024-12-16 20:40:55 +0000 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-12-20 22:34:02 +0100 |
| commit | 06fa229ceb36898e68022b5654c017d2c6582d7d (patch) | |
| tree | db540d16164012b660f6096819f5288356749f39 /fs/netfs/write_collect.c | |
| parent | netfs: Add a tracepoint to log the lifespan of folio_queue structs (diff) | |
| download | linux-06fa229ceb36898e68022b5654c017d2c6582d7d.tar.gz linux-06fa229ceb36898e68022b5654c017d2c6582d7d.zip | |
netfs: Abstract out a rolling folio buffer implementation
A rolling buffer is a series of folios held in a list of folio_queues. New
folios and folio_queue structs may be inserted at the head simultaneously
with spent ones being removed from the tail without the need for locking.
The rolling buffer includes an iov_iter and it has to be careful managing
this as the list of folio_queues is extended such that an oops doesn't
incurred because the iterator was pointing to the end of a folio_queue
segment that got appended to and then removed.
We need to use the mechanism twice, once for read and once for write, and,
in future patches, we will use a second rolling buffer to handle bounce
buffering for content encryption.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-6-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/netfs/write_collect.c')
| -rw-r--r-- | fs/netfs/write_collect.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c index ca3a11ed9b54..364c1f9d5815 100644 --- a/fs/netfs/write_collect.c +++ b/fs/netfs/write_collect.c @@ -83,9 +83,9 @@ end_wb: static void netfs_writeback_unlock_folios(struct netfs_io_request *wreq, unsigned int *notes) { - struct folio_queue *folioq = wreq->buffer; + struct folio_queue *folioq = wreq->buffer.tail; unsigned long long collected_to = wreq->collected_to; - unsigned int slot = wreq->buffer_head_slot; + unsigned int slot = wreq->buffer.first_tail_slot; if (wreq->origin == NETFS_PGPRIV2_COPY_TO_CACHE) { if (netfs_pgpriv2_unlock_copied_folios(wreq)) @@ -94,7 +94,9 @@ static void netfs_writeback_unlock_folios(struct netfs_io_request *wreq, } if (slot >= folioq_nr_slots(folioq)) { - folioq = netfs_delete_buffer_head(wreq); + folioq = rolling_buffer_delete_spent(&wreq->buffer); + if (!folioq) + return; slot = 0; } @@ -134,9 +136,9 @@ static void netfs_writeback_unlock_folios(struct netfs_io_request *wreq, folioq_clear(folioq, slot); slot++; if (slot >= folioq_nr_slots(folioq)) { - if (READ_ONCE(wreq->buffer_tail) == folioq) - break; - folioq = netfs_delete_buffer_head(wreq); + folioq = rolling_buffer_delete_spent(&wreq->buffer); + if (!folioq) + goto done; slot = 0; } @@ -144,8 +146,9 @@ static void netfs_writeback_unlock_folios(struct netfs_io_request *wreq, break; } - wreq->buffer = folioq; - wreq->buffer_head_slot = slot; + wreq->buffer.tail = folioq; +done: + wreq->buffer.first_tail_slot = slot; } /* |