3193b25a5a
extended attributes, the kernel can panic with either "ffs_truncate3" or with "softdep_deallocate_dependencies: dangling deps". The problem arises because the flushbuflist() function which is called to clear out buffers is passed either the V_NORMAL flag to indicate that it should flush buffer associated with the contents of the file or the V_ALT flag to indicate that it should flush the buffers associated with the extended attribute data. The buffers containing the extended attribute data are identified by having their BX_ALTDATA flag set in the buffer's b_xflags field. The BX_ALTDATA flag is set on the buffer when the extended attribute block is first allocated or when its contents are read in from the disk. On a busy system, a buffer may be reused for another purpose, but the contents of the block that it contained continues to be held in the main page cache. Each physical page is identified as holding the contents of a logical block within a specified file (identified by a vnode). When a request is made to read a file, the kernel first looks for the block in the existing buffers. If it is not found there, it checks the page cache to see if it is still there. If it is found in the page cache, then it is remapped into a new buffer thus avoiding the need to read it in from the disk. The bug is that when a buffer request made for an extended attribute is fulfilled by reconstituting a buffer from the page cache rather than reading it in from disk, the BX_ALTDATA flag was not being set. Thus the flushbuflist() function would never clear it out and the "ffs_truncate3" panic would occur because the vnode being cleared still had buffers on its clean-buffer list. If the extended attribute was being updated, it is first read, then updated, and finally written. If the read is fulfilled by reconstituting the buffer from the page cache the BX_ALTDATA flag was not set and thus the dirty buffer would never be flushed by flushbuflist(). Eventually the buffer would be recycled. Since it was never written it would have an unfinished dependency which would trigger the "softdep_deallocate_dependencies: dangling deps" panic. The fix is to ensure that the BX_ALTDATA flag is set when a buffer has been reconstituted from the page cache. PR: 230962 Reported by: 2t8mr7kx9f@protonmail.com Reviewed by: kib Tested by: Peter Holm MFC after: 1 week Sponsored by: Netflix |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README | ||
| README.md | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD
FreeBSD is an operating system used to power modern servers, desktops, and embedded platforms. A large community has continually developed it for more than thirty years. Its advanced networking, security, and storage features have made FreeBSD the platform of choice for many of the busiest web sites and most pervasive embedded networking and storage devices.
For copyright information, please see the file COPYRIGHT in this directory. Additional copyright information also exists for some sources in this tree - please see the specific source directories for more information.
The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree. See build(7), config(8), https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html, and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information, including setting make(1) variables.
Source Roadmap:
bin System/user commands.
cddl Various commands and libraries under the Common Development
and Distribution License.
contrib Packages contributed by 3rd parties.
crypto Cryptography stuff (see crypto/README).
etc Template files for /etc.
gnu Various commands and libraries under the GNU Public License.
Please see gnu/COPYING* for more information.
include System include files.
kerberos5 Kerberos5 (Heimdal) package.
lib System libraries.
libexec System daemons.
release Release building Makefile & associated tools.
rescue Build system for statically linked /rescue utilities.
sbin System commands.
secure Cryptographic libraries and commands.
share Shared resources.
stand Boot loader sources.
sys Kernel sources.
sys/<arch>/conf Kernel configuration files. GENERIC is the configuration
used in release builds. NOTES contains documentation of
all possible entries.
tests Regression tests which can be run by Kyua. See tests/README
for additional information.
tools Utilities for regression testing and miscellaneous tasks.
usr.bin User commands.
usr.sbin System administration commands.
For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see:
https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.html