- 07 5月, 2014 2 次提交
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由 Al Viro 提交于
iov_iter-using variant of generic_file_aio_read(). Some callers converted. Note that it's still not quite there for use as ->read_iter() - we depend on having zero iter->iov_offset in O_DIRECT case. Fortunately, that's true for all converted callers (and for generic_file_aio_read() itself). Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 08 4月, 2014 1 次提交
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由 Kirill A. Shutemov 提交于
filemap_map_pages() is generic implementation of ->map_pages() for filesystems who uses page cache. It should be safe to use filemap_map_pages() for ->map_pages() if filesystem use filemap_fault() for ->fault(). Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Dave Chinner <david@fromorbit.com> Cc: Ning Qu <quning@gmail.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 06 1月, 2014 1 次提交
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由 Niels de Vos 提交于
A fileid in NFS is a uint64. There are some occurrences where dprintk() outputs a signed fileid. This leads to confusion and more difficult to read debugging (negative fileids matching positive inode numbers). Signed-off-by: NNiels de Vos <ndevos@redhat.com> CC: Santosh Pradhan <spradhan@redhat.com> Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
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- 25 10月, 2013 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 04 9月, 2013 1 次提交
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由 Andy Adamson 提交于
We must avoid buffering a WRITE that is using a credential key (e.g. a GSS context key) that is about to expire or has expired. We currently will paint ourselves into a corner by returning success to the applciation for such a buffered WRITE, only to discover that we do not have permission when we attempt to flush the WRITE (and potentially associated COMMIT) to disk. Use the RPC layer credential key timeout and expire routines which use a a watermark, gss_key_expire_timeo. We test the key in nfs_file_write. If a WRITE is using a credential with a key that will expire within watermark seconds, flush the inode in nfs_write_end and send only NFS_FILE_SYNC WRITEs by adding nfs_ctx_key_to_expire to nfs_need_sync_write. Note that this results in single page NFS_FILE_SYNC WRITEs. Signed-off-by: NAndy Adamson <andros@netapp.com> [Trond: removed a pr_warn_ratelimited() for now] Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 22 8月, 2013 1 次提交
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由 Trond Myklebust 提交于
Add tracepoints for inode attribute updates, attribute revalidation, writeback start/end fsync start/end, attribute change start/end, permission check start/end. The intention is to enable performance tracing using 'perf'as well as improving debugging. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 04 7月, 2013 1 次提交
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由 Mel Gorman 提交于
VM page reclaim uses dirty and writeback page states to determine if flushers are cleaning pages too slowly and that page reclaim should stall waiting on flushers to catch up. Page state in NFS is a bit more complex and a clean page can be unreclaimable due to being unstable which is effectively "dirty" from the perspective of the VM from reclaim context. Similarly, if the inode is currently being committed then it's similar to being under writeback. This patch adds a is_dirty_writeback() handled for NFS that checks if a pages backing inode is being committed and should be accounted as writeback and if a page has private state indicating that it is effectively dirty. Signed-off-by: NMel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Cc: Zlatko Calusic <zcalusic@bitsync.net> Cc: dormando <dormando@rydia.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 22 5月, 2013 1 次提交
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由 Lukas Czerner 提交于
Currently there is no way to truncate partial page where the end truncate point is not at the end of the page. This is because it was not needed and the functionality was enough for file system truncate operation to work properly. However more file systems now support punch hole feature and it can benefit from mm supporting truncating page just up to the certain point. Specifically, with this functionality truncate_inode_pages_range() can be changed so it supports truncating partial page at the end of the range (currently it will BUG_ON() if 'end' is not at the end of the page). This commit changes the invalidatepage() address space operation prototype to accept range to be invalidated and update all the instances for it. We also change the block_invalidatepage() in the same way and actually make a use of the new length argument implementing range invalidation. Actual file system implementations will follow except the file systems where the changes are really simple and should not change the behaviour in any way .Implementation for truncate_page_range() which will be able to accept page unaligned ranges will follow as well. Signed-off-by: NLukas Czerner <lczerner@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com>
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- 09 4月, 2013 1 次提交
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由 Trond Myklebust 提交于
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 23 2月, 2013 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 18 12月, 2012 1 次提交
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由 Andrew Morton 提交于
But the kernel decided to call it "origin" instead. Fix most of the sites. Acked-by: NHugh Dickins <hughd@google.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 10月, 2012 1 次提交
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由 Konstantin Khlebnikov 提交于
Move actual pte filling for non-linear file mappings into the new special vma operation: ->remap_pages(). Filesystems must implement this method to get non-linear mapping support, if it uses filemap_fault() then generic_file_remap_pages() can be used. Now device drivers can implement this method and obtain nonlinear vma support. Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> #arch/tile Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 29 9月, 2012 2 次提交
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由 Trond Myklebust 提交于
This is to ensure that we don't clear the NFS_CONTEXT_RESEND_WRITES flag while there are still writes that haven't been resent. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Trond Myklebust 提交于
If the server reboots before it can commit the unstable writes to disk, then nfs_commit_release_pages() will detect this when it compares the verifier returned by COMMIT to the one returned by WRITE. When this happens, the client needs to resend those writes in order to guarantee that they make it to stable storage. This patch adds a signalling mechanism to notify fsync() that it needs to retry all writes before it can exit. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 12 9月, 2012 1 次提交
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由 Trond Myklebust 提交于
We need to ensure that if the call to filemap_write_and_wait_range() fails, then we report that error back to the application. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 01 8月, 2012 3 次提交
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由 Mel Gorman 提交于
Implement the new swapfile a_ops for NFS and hook up ->direct_IO. This will set the NFS socket to SOCK_MEMALLOC and run socket reconnect under PF_MEMALLOC as well as reset SOCK_MEMALLOC before engaging the protocol ->connect() method. PF_MEMALLOC should allow the allocation of struct socket and related objects and the early (re)setting of SOCK_MEMALLOC should allow us to receive the packets required for the TCP connection buildup. [jlayton@redhat.com: Restore PF_MEMALLOC task flags in all cases] [dfeng@redhat.com: Fix handling of multiple swap files] [a.p.zijlstra@chello.nl: Original patch] Signed-off-by: NMel Gorman <mgorman@suse.de> Acked-by: NRik van Riel <riel@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Neil Brown <neilb@suse.de> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Mel Gorman 提交于
Replace all relevant occurences of page->index and page->mapping in the NFS client with the new page_file_index() and page_file_mapping() functions. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NMel Gorman <mgorman@suse.de> Acked-by: NRik van Riel <riel@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Neil Brown <neilb@suse.de> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jeff Layton 提交于
We have no mechanism to emulate LOCK_MAND locks on NFSv4, so explicitly return -EINVAL if someone requests it. Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 31 7月, 2012 3 次提交
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由 Bryan Schumaker 提交于
This patch exports symbols needed by the v4 module. In addition, I also switch over to using IS_ENABLED() to check if CONFIG_NFS_V4 or CONFIG_NFS_V4_MODULE are set. The module (nfs4.ko) will be created in the same directory as nfs.ko and will be automatically loaded the first time you try to mount over NFS v4. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Bryan Schumaker 提交于
The module (nfs2.ko) will be created in the same directory as nfs.ko and will be automatically loaded the first time you try to mount over NFS v2. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Jeff Layton 提交于
We've had some reports of a deadlock where rpciod ends up with a stack trace like this: PID: 2507 TASK: ffff88103691ab40 CPU: 14 COMMAND: "rpciod/14" #0 [ffff8810343bf2f0] schedule at ffffffff814dabd9 #1 [ffff8810343bf3b8] nfs_wait_bit_killable at ffffffffa038fc04 [nfs] #2 [ffff8810343bf3c8] __wait_on_bit at ffffffff814dbc2f #3 [ffff8810343bf418] out_of_line_wait_on_bit at ffffffff814dbcd8 #4 [ffff8810343bf488] nfs_commit_inode at ffffffffa039e0c1 [nfs] #5 [ffff8810343bf4f8] nfs_release_page at ffffffffa038bef6 [nfs] #6 [ffff8810343bf528] try_to_release_page at ffffffff8110c670 #7 [ffff8810343bf538] shrink_page_list.clone.0 at ffffffff81126271 #8 [ffff8810343bf668] shrink_inactive_list at ffffffff81126638 #9 [ffff8810343bf818] shrink_zone at ffffffff8112788f #10 [ffff8810343bf8c8] do_try_to_free_pages at ffffffff81127b1e #11 [ffff8810343bf958] try_to_free_pages at ffffffff8112812f #12 [ffff8810343bfa08] __alloc_pages_nodemask at ffffffff8111fdad #13 [ffff8810343bfb28] kmem_getpages at ffffffff81159942 #14 [ffff8810343bfb58] fallback_alloc at ffffffff8115a55a #15 [ffff8810343bfbd8] ____cache_alloc_node at ffffffff8115a2d9 #16 [ffff8810343bfc38] kmem_cache_alloc at ffffffff8115b09b #17 [ffff8810343bfc78] sk_prot_alloc at ffffffff81411808 #18 [ffff8810343bfcb8] sk_alloc at ffffffff8141197c #19 [ffff8810343bfce8] inet_create at ffffffff81483ba6 #20 [ffff8810343bfd38] __sock_create at ffffffff8140b4a7 #21 [ffff8810343bfd98] xs_create_sock at ffffffffa01f649b [sunrpc] #22 [ffff8810343bfdd8] xs_tcp_setup_socket at ffffffffa01f6965 [sunrpc] #23 [ffff8810343bfe38] worker_thread at ffffffff810887d0 #24 [ffff8810343bfee8] kthread at ffffffff8108dd96 #25 [ffff8810343bff48] kernel_thread at ffffffff8100c1ca rpciod is trying to allocate memory for a new socket to talk to the server. The VM ends up calling ->releasepage to get more memory, and it tries to do a blocking commit. That commit can't succeed however without a connected socket, so we deadlock. Fix this by setting PF_FSTRANS on the workqueue task prior to doing the socket allocation, and having nfs_release_page check for that flag when deciding whether to do a commit call. Also, set PF_FSTRANS unconditionally in rpc_async_schedule since that function can also do allocations sometimes. Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com> Cc: stable@vger.kernel.org
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- 18 7月, 2012 3 次提交
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由 Bryan Schumaker 提交于
This patch moves the NFS v4 file functions into a new file that is only compiled when CONFIG_NFS_V4 is enabled. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Bryan Schumaker 提交于
This patch moves the NFS v3 file and directory inode functions into files that are only compiled whet CONFIG_NFS_V3 is enabled. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Bryan Schumaker 提交于
This patch moves the NFS v2 file and directory inode functions into files that are only compiled whet CONFIG_NFS_V2 is enabled. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 29 6月, 2012 2 次提交
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由 Bryan Schumaker 提交于
Delegations are a v4 feature, so push them out of the generic code. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Bryan Schumaker 提交于
v2 and v3 don't need to worry about doing a pnfs layoutcommit. Signed-off-by: NBryan Schumaker <bjschuma@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 02 6月, 2012 1 次提交
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由 Miklos Szeredi 提交于
NFSv4 can't do reliable opens in d_revalidate, since it cannot know whether a mount needs to be followed or not. It does check d_mountpoint() on the dentry, which can result in a weird error if the VFS found that the mount does not in fact need to be followed, e.g.: # mount --bind /mnt/nfs /mnt/nfs-clone # echo something > /mnt/nfs/tmp/bar # echo x > /tmp/file # mount --bind /tmp/file /mnt/nfs-clone/tmp/bar # cat /mnt/nfs/tmp/bar cat: /mnt/nfs/tmp/bar: Not a directory Which should, by any sane filesystem, result in "something" being printed. So instead do the open in f_op->open() and in the unlikely case that the cached dentry turned out to be invalid, drop the dentry and return EOPENSTALE to let the VFS retry. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> CC: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 25 5月, 2012 1 次提交
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由 Andy Adamson 提交于
Keep track of the number of bytes read or written via buffered, direct, and mem-mapped i/o for use by mdsthreshold size_io hints. Signed-off-by: NAndy Adamson <andros@netapp.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 09 5月, 2012 1 次提交
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由 Trond Myklebust 提交于
If we hold a delegation then we know that it should be safe to continue to cache the data beyond the close(). However since the process that wrote the data may die after close(), we may still want to send the data to server before those RPCSEC_GSS credentials expire. We therefore compromise by starting writeback to the server, but don't wait for completion. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 29 3月, 2012 1 次提交
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由 David Howells 提交于
Remove all #inclusions of asm/system.h preparatory to splitting and killing it. Performed with the following command: perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *` Signed-off-by: NDavid Howells <dhowells@redhat.com>
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- 01 2月, 2012 1 次提交
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由 Trond Myklebust 提交于
Ensure that nfs_vm_page_mkwrite() waits for the page writeback to complete before the application is allowed to modify page contents. The main reason for wanting to do this in NFS is to ensure that the server doesn't get confused if we have to resend the RPC request due to a dropped/missed reply. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 05 1月, 2012 1 次提交
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由 NeilBrown 提交于
From c6d615d2b97fe305cbf123a8751ced859dca1d5e Mon Sep 17 00:00:00 2001 From: NeilBrown <neilb@suse.de> Date: Wed, 16 Nov 2011 09:39:05 +1100 Subject: [PATCH] NFS - fix recent breakage to NFS error handling. commit 02c24a82 made a small and presumably unintended change to write error handling in NFS. Previously an error from filemap_write_and_wait_range would only be of interest if nfs_file_fsync did not return an error. After this commit, an error from filemap_write_and_wait_range would mean that (the rest of) nfs_file_fsync would not even be called. This means that: 1/ you are more likely to see EIO than e.g. EDQUOT or ENOSPC. 2/ NFS_CONTEXT_ERROR_WRITE remains set for longer so more writes are synchronous. This patch restores previous behaviour. Cc: stable@kernel.org Cc: Josef Bacik <josef@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: NNeilBrown <neilb@suse.de> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 16 12月, 2011 1 次提交
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由 Trond Myklebust 提交于
After commit 06222e49 (fs: handle SEEK_HOLE/SEEK_DATA properly in all fs's that define their own llseek) the behaviour of llseek() was changed so that it always revalidates the file size. The bug appears to be due to a logic error in the afore-mentioned commit, which always evaluates to 'true'. Reported-by: NRoel Kluin <roel.kluin@gmail.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com> Cc: stable@vger.kernel.org [>=3.1]
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- 05 11月, 2011 2 次提交
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由 Jeff Layton 提交于
...a remove a set of forward declarations. Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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由 Jeff Layton 提交于
commit d953126a changed how nfs_atomic_lookup handles an -EISDIR return from an OPEN call. Prior to that patch, that caused the client to fall back to doing a normal lookup. When that patch went in, the code began returning that error to userspace. The d_revalidate codepath however never had the corresponding change, so it was still possible to end up with a NULL ctx->state pointer after that. That patch caused a regression. When we attempt to open a directory that does not have a cached dentry, that open now errors out with EISDIR. If you attempt the same open with a cached dentry, it will succeed. Fix this by reverting the change in nfs_atomic_lookup and allowing attempts to open directories to fall back to a normal lookup Also, add a NFSv4-specific f_ops->open routine that just returns -ENOTDIR. This should never be called if things are working properly, but if it ever is, then the dprintk may help in debugging. To facilitate this, a new file_operations field is also added to the nfs_rpc_ops struct. Cc: stable@kernel.org Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 03 11月, 2011 1 次提交
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由 Rakib Mullick 提交于
Fix the following unused variable warning. fs/nfs/file.c: In function ‘nfs_file_release’: fs/nfs/file.c:140:17: warning: unused variable ‘dentry’ fs/nfs/file.c: In function ‘nfs_file_read’: fs/nfs/file.c:237:9: warning: unused variable ‘count’ Signed-off-by: NRakib Mullick <rakib.mullick@gmail.com> Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
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- 28 10月, 2011 2 次提交
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由 Andi Kleen 提交于
This makes NFS follow the standard generic_file_llseek locking scheme. Cc: Trond.Myklebust@netapp.com Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NChristoph Hellwig <hch@lst.de>
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由 Andi Kleen 提交于
The i_mutex lock use of generic _file_llseek hurts. Independent processes accessing the same file synchronize over a single lock, even though they have no need for synchronization at all. Under high utilization this can cause llseek to scale very poorly on larger systems. This patch does some rethinking of the llseek locking model: First the 64bit f_pos is not necessarily atomic without locks on 32bit systems. This can already cause races with read() today. This was discussed on linux-kernel in the past and deemed acceptable. The patch does not change that. Let's look at the different seek variants: SEEK_SET: Doesn't really need any locking. If there's a race one writer wins, the other loses. For 32bit the non atomic update races against read() stay the same. Without a lock they can also happen against write() now. The read() race was deemed acceptable in past discussions, and I think if it's ok for read it's ok for write too. => Don't need a lock. SEEK_END: This behaves like SEEK_SET plus it reads the maximum size too. Reading the maximum size would have the 32bit atomic problem. But luckily we already have a way to read the maximum size without locking (i_size_read), so we can just use that instead. Without i_mutex there is no synchronization with write() anymore, however since the write() update is atomic on 64bit it just behaves like another racy SEEK_SET. On non atomic 32bit it's the same as SEEK_SET. => Don't need a lock, but need to use i_size_read() SEEK_CUR: This has a read-modify-write race window on the same file. One could argue that any application doing unsynchronized seeks on the same file is already broken. But for the sake of not adding a regression here I'm using the file->f_lock to synchronize this. Using this lock is much better than the inode mutex because it doesn't synchronize between processes. => So still need a lock, but can use a f_lock. This patch implements this new scheme in generic_file_llseek. I dropped generic_file_llseek_unlocked and changed all callers. Signed-off-by: NAndi Kleen <ak@linux.intel.com> Signed-off-by: NChristoph Hellwig <hch@lst.de>
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- 21 7月, 2011 1 次提交
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由 Josef Bacik 提交于
Btrfs needs to be able to control how filemap_write_and_wait_range() is called in fsync to make it less of a painful operation, so push down taking i_mutex and the calling of filemap_write_and_wait() down into the ->fsync() handlers. Some file systems can drop taking the i_mutex altogether it seems, like ext3 and ocfs2. For correctness sake I just pushed everything down in all cases to make sure that we keep the current behavior the same for everybody, and then each individual fs maintainer can make up their mind about what to do from there. Thanks, Acked-by: NJan Kara <jack@suse.cz> Signed-off-by: NJosef Bacik <josef@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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