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2020-11-199p: apply review requests for fid refcountingDominique Martinet1-1/+1
Fix style issues in parent commit ("apply review requests for fid refcounting"), no functional change. Link: http://lkml.kernel.org/r/1605802012-31133-2-git-send-email-asmadeus@codewreck.org Fixes: 6636b6dcc3db ("9p: add refcount to p9_fid struct") Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
2020-11-199p: add refcount to p9_fid structJianyong Wu1-1/+9
Fix race issue in fid contention. Eric's and Greg's patch offer a mechanism to fix open-unlink-f*syscall bug in 9p. But there is race issue in fid parallel accesses. As Greg's patch stores all of fids from opened files into according inode, so all the lookup fid ops can retrieve fid from inode preferentially. But there is no mechanism to handle the fid contention issue. For example, there are two threads get the same fid in the same time and one of them clunk the fid before the other thread ready to discard the fid. In this scenario, it will lead to some fatal problems, even kernel core dump. I introduce a mechanism to fix this race issue. A counter field introduced into p9_fid struct to store the reference counter to the fid. When a fid is allocated from the inode or dentry, the counter will increase, and will decrease at the end of its occupation. It is guaranteed that the fid won't be clunked before the reference counter go down to 0, then we can avoid the clunked fid to be used. tests: race issue test from the old test case: for file in {01..50}; do touch f.${file}; done seq 1 1000 | xargs -n 1 -P 50 -I{} cat f.* > /dev/null open-unlink-f*syscall test: I have tested for f*syscall include: ftruncate fstat fchown fchmod faccessat. Link: http://lkml.kernel.org/r/20200923141146.90046-5-jianyong.wu@arm.com Fixes: 478ba09edc1f ("fs/9p: search open fids first") Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
2020-11-03fs/9p: track open fidsGreg Kurz1-0/+1
This patch adds accounting of open fids in a list hanging off the i_private field of the corresponding inode. This allows faster lookups compared to searching the full 9p client list. The lookup code is modified accordingly. Link: http://lkml.kernel.org/r/20200923141146.90046-3-jianyong.wu@arm.com Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188Thomas Gleixner1-16/+1
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to free software foundation 51 franklin street fifth floor boston ma 02111 1301 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 27 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190528170026.981318839@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-039p: use clone_fid()Al Viro1-1/+4
in a bunch of places it cleans the things up Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-08-039p: fix braino introduced in "9p: new helper - v9fs_parent_fid()"Al Viro1-0/+4
In v9fs_vfs_rename() we need to clone the parents' fids, not just find them. Spotted-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-299p: new helper - v9fs_parent_fid()Al Viro1-0/+4
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-289p: v9fs_fid_add() can't fail nowAl Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-28v9fs: get rid of v9fs_dentryAl Viro1-20/+0
->d_fsdata can act as hlist_head... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-279p: turn fid->dlist into hlistAl Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-279p: don't bother with private lock in ->d_fsdata; dentry->d_lock will do just fineAl Viro1-2/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-15fs/9p: Prevent multiple inclusion of same headerAneesh Kumar K.V1-1/+3
Add necessary #ifndef #endif blocks to avoid mulitple inclusion of same headers Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2011-03-15fs/9p: Add fid to inode in cached modeAneesh Kumar K.V1-0/+1
The fid attached to inode will be opened O_RDWR mode and is used for dirty page writeback only. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2008-05-149p: Documentation updatesEric Van Hensbergen1-0/+15
The kernel-doc comments of much of the 9p system have been in disarray since reorganization. This patch fixes those problems, adds additional documentation and a template book which collects the 9p information. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2007-08-239p: remove deprecated v9fs_fid_lookup_remove()Eric Van Hensbergen1-1/+0
This patch removes the v9fs_fid_lookup_remove which is no longer used. Based on original patch from Adrian Bunk <bunk@stusta.de> which used #if 0 to isolate the code. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2007-07-149p: Reorganization of 9p file system codeLatchesar Ionkov1-36/+7
This patchset moves non-filesystem interfaces of v9fs from fs/9p to net/9p. It moves the transport, packet marshalling and connection layers to net/9p leaving only the VFS related files in fs/9p. This work is being done in preparation for in-kernel 9p servers as well as alternate 9p clients (other than VFS). Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2007-01-26[PATCH] 9p: fix segfault caused by race condition in meta-data operationsEric Van Hensbergen1-0/+5
Running dbench multithreaded exposed a race condition where fid structures were removed while in use. This patch adds semaphores to meta-data operations to protect the fid structure. Some cleanup of error-case handling in the inode operations is also included. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-03-25[PATCH] v9fs: update license boilerplateEric Van Hensbergen1-3/+2
Update license boilerplate to specify GPLv2 and remove the (at your option clause). This change was agreed to by all the copyright holders (approvals can be found on v9fs-developer mailing list). Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-02[PATCH] v9fs: simplify fid mappingEric Van Hensbergen1-1/+0
v9fs has been plagued by an over-complicated approach trying to map Linux dentry semantics to Plan 9 fid semantics. Our previous approach called for aggressive flushing of the dcache resulting in several problems (including wierd cwd behavior when running /bin/pwd). This patch dramatically simplifies our handling of this fid management. Fids will not be clunked as promptly, but the new approach is more functionally correct. We now clunk un-open fids only when their dentry ref_count reaches 0 (and d_delete is called). Another simplification is we no longer seek to match fids to the process-id or uid of the action initiator. The uid-matching will need to be revisited when we fix the security model. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-02[PATCH] v9fs: fix atomic create openLatchesar Ionkov1-3/+2
In order to assure atomic create+open v9fs stores the open fid produced by v9fs_vfs_create in the dentry, from where v9fs_file_open retrieves it and associates it with the open file. This patch modifies v9fs to use nameidata.intent.open values to do the atomic create+open. Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28[PATCH] v9fs: fix races in fid allocationLatchesar Ionkov1-2/+5
Fid management cleanup. The patch attempts to fix the races in dentry's fid management. Dentries don't keep the opened fids anymore, they are moved to the file structs. Ideally there should be no more than one fid with fidcreate equal to zero in the dentry's list of fids. v9fs_fid_create initializes the important fields (fid, fidcreated) before v9fs_fid is added to the list. v9fs_fid_lookup returns only fids that are not created by v9fs_create. v9fs_fid_get_created returns the fid created by the same process by v9fs_create (if any) and removes it from dentry's list Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Cc: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09[PATCH] v9fs: debug and support routinesEric Van Hensbergen1-0/+57
This part of the patch contains debug and other misc routines. Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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