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![]() [ Upstream commit 8175c864391753b210f3dcfae1aeed686a226ebb ]
Script to reproduce:
f2fs_io write 1 0 1881 rand dsync testfile
f2fs_io fallocate 0 7708672 4096 testfile
f2fs_io write 1 1881 1 rand buffered testfile
fsync testfile
umount
mount
f2fs_io precache_extents testfile
When the data layout is something like this:
dnode1: dnode2:
[0] A [0] NEW_ADDR
[1] A+1 [1] 0x0
...
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
During precache_extents, we map the last block(valid blkaddr) in dnode1:
map->m_flags |= F2FS_MAP_MAPPED;
map->m_pblk = blkaddr(valid blkaddr);
map->m_len = 1;
then we goto next_dnode, meet the first block in dnode2(hole), goto sync_out:
map->m_flags & F2FS_MAP_MAPPED == true, and we make zero-sized extent:
map->m_len = 1
ofs = start_pgofs - map->m_lblk = 1882 - 1881 = 1
ei.fofs = start_pgofs = 1882
ei.len = map->m_len - ofs = 1 - 1 = 0
Rebased on patch[1], this patch can cover these cases to avoid zero-sized extent:
A,B,C is valid blkaddr
case1:
dnode1: dnode2:
[0] A [0] NEW_ADDR
[1] A+1 [1] 0x0
... ....
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
case2:
dnode1: dnode2:
[0] A [0] C (C!=B+1)
[1] A+1 [1] C+1
... ....
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
case3:
dnode1: dnode2:
[0] A [0] C (C!=B+2)
[1] A+1 [1] C+1
... ....
[1015] A+1015
[1016] B (B!=A+1016)
[1017] B+1 [1017] 0x0
[1] https://lore.kernel.org/linux-f2fs-devel/20250912081250.44383-1-chao@kernel.org/
Fixes:
|
||
---|---|---|
arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
fs | ||
include | ||
init | ||
io_uring | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
rust | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
.rustfmt.toml | ||
COPYING | ||
CREDITS | ||
Kbuild | ||
Kconfig | ||
MAINTAINERS | ||
Makefile | ||
README |
Linux kernel
There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first.
In order to build the documentation, use make htmldocs
or
make pdfdocs
. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.