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 --- drivers/md/persistent-data/dm-space-map-metadata.h | 45 ++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 drivers/md/persistent-data/dm-space-map-metadata.h (limited to 'drivers/md/persistent-data/dm-space-map-metadata.h') diff --git a/drivers/md/persistent-data/dm-space-map-metadata.h b/drivers/md/persistent-data/dm-space-map-metadata.h new file mode 100644 index 000000000..ca5c3e532 --- /dev/null +++ b/drivers/md/persistent-data/dm-space-map-metadata.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2011 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#ifndef DM_SPACE_MAP_METADATA_H +#define DM_SPACE_MAP_METADATA_H + +#include "dm-transaction-manager.h" + +#define DM_SM_METADATA_BLOCK_SIZE (4096 >> SECTOR_SHIFT) + +/* + * The metadata device is currently limited in size. + * + * We have one block of index, which can hold 255 index entries. Each + * index entry contains allocation info about ~16k metadata blocks. + */ +#define DM_SM_METADATA_MAX_BLOCKS (255 * ((1 << 14) - 64)) +#define DM_SM_METADATA_MAX_SECTORS (DM_SM_METADATA_MAX_BLOCKS * DM_SM_METADATA_BLOCK_SIZE) + +/* + * Unfortunately we have to use two-phase construction due to the cycle + * between the tm and sm. + */ +struct dm_space_map *dm_sm_metadata_init(void); + +/* + * Create a fresh space map. + */ +int dm_sm_metadata_create(struct dm_space_map *sm, + struct dm_transaction_manager *tm, + dm_block_t nr_blocks, + dm_block_t superblock); + +/* + * Open from a previously-recorded root. + */ +int dm_sm_metadata_open(struct dm_space_map *sm, + struct dm_transaction_manager *tm, + void *root_le, size_t len); + +#endif /* DM_SPACE_MAP_METADATA_H */ -- cgit v1.3.1