From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 19:20:30 -0300 Subject: netfs: zero the tail of a short DIO/unbuffered read The buffered read collector zero-fills the tail of a short read that stops below the inode's i_size (netfs_clear_unread()), so a read that races an extending write still returns the expected number of bytes. The non-buffered collector path does no such thing: it just records how much was transferred. Add the same zero-fill for the non-buffered case, gated on NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short result from it is known to be safe to treat as a hole, as opposed to NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of the file and should be reported short as-is. Only CLEAR_TAIL should zero-fill here; a real EOF must stay a real short read. No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest, so this is inert on its own -- a following change teaches cifs to set it in the one case that needs it. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- Documentation/devicetree/changesets.rst | 37 +++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 Documentation/devicetree/changesets.rst (limited to 'Documentation/devicetree/changesets.rst') diff --git a/Documentation/devicetree/changesets.rst b/Documentation/devicetree/changesets.rst new file mode 100644 index 000000000..2091468d4 --- /dev/null +++ b/Documentation/devicetree/changesets.rst @@ -0,0 +1,37 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================== +Devicetree Changesets +===================== + +A Devicetree changeset is a method which allows one to apply changes +in the live tree in such a way that either the full set of changes +will be applied, or none of them will be. If an error occurs partway +through applying the changeset, then the tree will be rolled back to the +previous state. A changeset can also be removed after it has been +applied. + +When a changeset is applied, all of the changes get applied to the tree +at once before emitting OF_RECONFIG notifiers. This is so that the +receiver sees a complete and consistent state of the tree when it +receives the notifier. + +The sequence of a changeset is as follows. + +1. of_changeset_init() - initializes a changeset + +2. A number of DT tree change calls, of_changeset_attach_node(), + of_changeset_detach_node(), of_changeset_add_property(), + of_changeset_remove_property, of_changeset_update_property() to prepare + a set of changes. No changes to the active tree are made at this point. + All the change operations are recorded in the of_changeset 'entries' + list. + +3. of_changeset_apply() - Apply the changes to the tree. Either the + entire changeset will get applied, or if there is an error the tree will + be restored to the previous state. The core ensures proper serialization + through locking. An unlocked version __of_changeset_apply is available, + if needed. + +If a successfully applied changeset needs to be removed, it can be done +with of_changeset_revert(). -- cgit v1.3.1