netfs: zero the tail of a short DIO/unbuffered readgrafted

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 <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 60 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/Makefile b/drivers/accessibility/speakup/Makefile
new file mode 100644
index 000000000..14ba1cca8
--- /dev/null
+++ b/drivers/accessibility/speakup/Makefile
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_SPEAKUP_SYNTH_ACNTSA) += speakup_acntsa.o
+obj-$(CONFIG_SPEAKUP_SYNTH_ACNTPC) += speakup_acntpc.o
+obj-$(CONFIG_SPEAKUP_SYNTH_APOLLO) += speakup_apollo.o
+obj-$(CONFIG_SPEAKUP_SYNTH_AUDPTR) += speakup_audptr.o
+obj-$(CONFIG_SPEAKUP_SYNTH_BNS) += speakup_bns.o
+obj-$(CONFIG_SPEAKUP_SYNTH_DECTLK) += speakup_dectlk.o
+obj-$(CONFIG_SPEAKUP_SYNTH_DECEXT) += speakup_decext.o
+obj-$(CONFIG_SPEAKUP_SYNTH_DECPC) += speakup_decpc.o
+obj-$(CONFIG_SPEAKUP_SYNTH_DTLK) += speakup_dtlk.o
+obj-$(CONFIG_SPEAKUP_SYNTH_KEYPC) += speakup_keypc.o
+obj-$(CONFIG_SPEAKUP_SYNTH_LTLK) += speakup_ltlk.o
+obj-$(CONFIG_SPEAKUP_SYNTH_SOFT) += speakup_soft.o
+obj-$(CONFIG_SPEAKUP_SYNTH_SPKOUT) += speakup_spkout.o
+obj-$(CONFIG_SPEAKUP_SYNTH_TXPRT) += speakup_txprt.o
+obj-$(CONFIG_SPEAKUP_SYNTH_DUMMY) += speakup_dummy.o
+
+obj-$(CONFIG_SPEAKUP) += speakup.o
+speakup-y := \
+	buffers.o \
+	devsynth.o \
+	i18n.o \
+	fakekey.o \
+	main.o \
+	keyhelp.o \
+	kobjects.o \
+	selection.o \
+	spk_ttyio.o \
+	synth.o \
+	thread.o \
+	varhandlers.o
+speakup-$(CONFIG_SPEAKUP_SERIALIO) += serialio.o
+
+
+clean-files := mapdata.h speakupmap.h
+
+
+# Generate mapdata.h from headers
+hostprogs += makemapdata
+makemapdata-objs := makemapdata.o
+
+quiet_cmd_mkmap = MKMAP   $@
+      cmd_mkmap = TOPDIR=$(srctree) SPKDIR=$(src) $(obj)/makemapdata > $@
+
+$(obj)/mapdata.h: $(obj)/makemapdata
+	$(call cmd,mkmap)
+
+
+# Generate speakupmap.h from mapdata.h
+hostprogs += genmap
+genmap-objs := genmap.o
+$(obj)/genmap.o: $(obj)/mapdata.h
+
+quiet_cmd_genmap = GENMAP  $@
+      cmd_genmap = $(obj)/genmap $< > $@
+
+$(obj)/speakupmap.h: $(src)/speakupmap.map $(obj)/genmap
+	$(call cmd,genmap)
+
+$(obj)/main.o: $(obj)/speakupmap.h