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, 24 insertions, 0 deletions

diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
new file mode 100644
index 000000000..9fe4ce9cf
--- /dev/null
+++ b/drivers/mtd/devices/Makefile
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# linux/drivers/mtd/devices/Makefile
+#
+
+obj-$(CONFIG_MTD_DOCG3)		+= docg3.o
+obj-$(CONFIG_MTD_SLRAM)		+= slram.o
+obj-$(CONFIG_MTD_PHRAM)		+= phram.o
+obj-$(CONFIG_MTD_PMC551)	+= pmc551.o
+obj-$(CONFIG_MTD_MS02NV)	+= ms02-nv.o
+obj-$(CONFIG_MTD_MTDRAM)	+= mtdram.o
+obj-$(CONFIG_MTD_BLOCK2MTD)	+= block2mtd.o
+obj-$(CONFIG_MTD_DATAFLASH)	+= mtd_dataflash.o
+obj-$(CONFIG_MTD_MCHP23K256)	+= mchp23k256.o
+obj-$(CONFIG_MTD_MCHP48L640)	+= mchp48l640.o
+obj-$(CONFIG_MTD_SPEAR_SMI)	+= spear_smi.o
+obj-$(CONFIG_MTD_SST25L)	+= sst25l.o
+obj-$(CONFIG_MTD_BCM47XXSFLASH)	+= bcm47xxsflash.o
+obj-$(CONFIG_MTD_ST_SPI_FSM)    += st_spi_fsm.o
+obj-$(CONFIG_MTD_POWERNV_FLASH)	+= powernv_flash.o
+obj-$(CONFIG_MTD_INTEL_DG)	+= mtd_intel_dg.o
+
+
+CFLAGS_docg3.o			+= -I$(src)