freebsd kernel with SKQ
df9f3d2faa
It seems that intended locking protocol for struct file f_offset field was as follows: f_offset should always be changed under the vnode lock (except fcntl(2) and lseek(2) did not followed the rules). Since read(2) uses shared vnode lock, FOFFSET_LOCKED block is additionally taken to serialize shared vnode lock owners. This was broken first by enabling shared lock on writes, then by fadvise changes, which moved f_offset assigned from under vnode lock, and last by vn_io_fault() doing chunked i/o. More, due to uio_offset not yet valid in vn_io_fault(), the range lock for reads was taken on the wrong region. Change the locking for f_offset to always use FOFFSET_LOCKED block, which is placed before rangelocks in the lock order. Extract foffset_lock() and foffset_unlock() functions which implements FOFFSET_LOCKED lock, and consistently lock f_offset with it in the vn_io_fault() both for reads and writes, even if MNTK_NO_IOPF flag is not set for the vnode mount. Indicate that f_offset is already valid for vn_read() and vn_write() calls from vn_io_fault() with FOF_OFFSET flag, and assert that all callers of vn_read() and vn_write() follow this protocol. Extract get_advice() function to calculate the POSIX_FADV_XXX value for the i/o region, and use it were appropriate. Reviewed by: jhb Tested by: pho MFC after: 2 weeks |
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ 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, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. 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. games Amusements. 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. sys Kernel sources. 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: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html