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266b5d02e1
When the SMB server reboots and the client immediately accesses the mount
point, a race condition can occur that causes operations to fail with
"Host is down" error.
Reproduction steps:
# Mount SMB share
mount -t cifs //192.168.245.109/TEST /mnt/ -o xxxx
ls /mnt
# Reboot server
ssh root@192.168.245.109 reboot
ssh root@192.168.245.109 /path/to/cifs_server_setup.sh
ssh root@192.168.245.109 systemctl stop firewalld
# Immediate access fails
ls /mnt
ls: cannot access '/mnt': Host is down
# But works if there is a delay
The issue is caused by a race condition between negotiate and reconnect.
The 20-second negotiate timeout mechanism can interfere with the normal
recovery process when both are triggered simultaneously.
ls cifsd
---------------------------------------------------
cifs_getattr
cifs_revalidate_dentry
cifs_get_inode_info
cifs_get_fattr
smb2_query_path_info
smb2_compound_op
SMB2_open_init
smb2_reconnect
cifs_negotiate_protocol
smb2_negotiate
cifs_send_recv
smb_send_rqst
wait_for_response
cifs_demultiplex_thread
cifs_read_from_socket
cifs_readv_from_socket
server_unresponsive
cifs_reconnect
__cifs_reconnect
cifs_abort_connection
mid->mid_state = MID_RETRY_NEEDED
cifs_wake_up_task
cifs_sync_mid_result
// case MID_RETRY_NEEDED
rc = -EAGAIN;
// In smb2_negotiate()
rc = -EHOSTDOWN;
The server_unresponsive() timeout triggers cifs_reconnect(), which aborts
ongoing mid requests and causes the ls command to receive -EAGAIN, leading
to -EHOSTDOWN.
Fix this by introducing a dedicated `neg_start` field to
precisely tracks when the negotiate process begins. The timeout check
now uses this accurate timestamp instead of `lstrp`, ensuring that:
1. Timeout is only triggered after negotiate has actually run for 20s
2. The mechanism doesn't interfere with concurrent recovery processes
3. Uninitialized timestamps (value 0) don't trigger false timeouts
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 | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .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 reStructuredText 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.