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 --- scripts/include/hash.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 scripts/include/hash.h (limited to 'scripts/include/hash.h') diff --git a/scripts/include/hash.h b/scripts/include/hash.h new file mode 100644 index 000000000..efa904368 --- /dev/null +++ b/scripts/include/hash.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef HASH_H +#define HASH_H + +static inline unsigned int hash_str(const char *s) +{ + /* fnv32 hash */ + unsigned int hash = 2166136261U; + + for (; *s; s++) + hash = (hash ^ *s) * 0x01000193; + return hash; +} + +/* simplified version of functions from include/linux/hash.h */ +#define GOLDEN_RATIO_32 0x61C88647 + +static inline unsigned int hash_32(unsigned int val) +{ + return 0x61C88647 * val; +} + +static inline unsigned int hash_ptr(const void *ptr) +{ + return hash_32((unsigned int)(unsigned long)ptr); +} + +#endif /* HASH_H */ -- cgit v1.3.1