mainlining shenanigans
7764d56baa
If we are able to load an existing inode cache off disk, we set the state
of the cache to BTRFS_CACHE_FINISHED, but we don't wake up any one waiting
for the cache to be available. This means that anyone waiting for the
cache to be available, waiting on the condition that either its state is
BTRFS_CACHE_FINISHED or its available free space is greather than zero,
can hang forever.
This could be observed running fstests with MOUNT_OPTIONS="-o inode_cache",
in particular test case generic/161 triggered it very frequently for me,
producing a trace like the following:
[63795.739712] BTRFS info (device sdc): enabling inode map caching
[63795.739714] BTRFS info (device sdc): disk space caching is enabled
[63795.739716] BTRFS info (device sdc): has skinny extents
[64036.653886] INFO: task btrfs-transacti:3917 blocked for more than 120 seconds.
[64036.654079] Not tainted 5.2.0-rc4-btrfs-next-50 #1
[64036.654143] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[64036.654232] btrfs-transacti D 0 3917 2 0x80004000
[64036.654239] Call Trace:
[64036.654258] ? __schedule+0x3ae/0x7b0
[64036.654271] schedule+0x3a/0xb0
[64036.654325] btrfs_commit_transaction+0x978/0xae0 [btrfs]
[64036.654339] ? remove_wait_queue+0x60/0x60
[64036.654395] transaction_kthread+0x146/0x180 [btrfs]
[64036.654450] ? btrfs_cleanup_transaction+0x620/0x620 [btrfs]
[64036.654456] kthread+0x103/0x140
[64036.654464] ? kthread_create_worker_on_cpu+0x70/0x70
[64036.654476] ret_from_fork+0x3a/0x50
[64036.654504] INFO: task xfs_io:3919 blocked for more than 120 seconds.
[64036.654568] Not tainted 5.2.0-rc4-btrfs-next-50 #1
[64036.654617] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[64036.654685] xfs_io D 0 3919 3633 0x00000000
[64036.654691] Call Trace:
[64036.654703] ? __schedule+0x3ae/0x7b0
[64036.654716] schedule+0x3a/0xb0
[64036.654756] btrfs_find_free_ino+0xa9/0x120 [btrfs]
[64036.654764] ? remove_wait_queue+0x60/0x60
[64036.654809] btrfs_create+0x72/0x1f0 [btrfs]
[64036.654822] lookup_open+0x6bc/0x790
[64036.654849] path_openat+0x3bc/0xc00
[64036.654854] ? __lock_acquire+0x331/0x1cb0
[64036.654869] do_filp_open+0x99/0x110
[64036.654884] ? __alloc_fd+0xee/0x200
[64036.654895] ? do_raw_spin_unlock+0x49/0xc0
[64036.654909] ? do_sys_open+0x132/0x220
[64036.654913] do_sys_open+0x132/0x220
[64036.654926] do_syscall_64+0x60/0x1d0
[64036.654933] entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fix this by adding a wake_up() call right after setting the cache state to
BTRFS_CACHE_FINISHED, at start_caching(), when we are able to load the
cache from disk.
Fixes:
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||
---|---|---|
arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | ||
.cocciconfig | ||
.get_maintainer.ignore | ||
.gitattributes | ||
.gitignore | ||
.mailmap | ||
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.