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* afs: Fix page leak on afs_write_begin() failureDavid Howells2020-10-291-12/+11
| | | | | | | | Fix the leak of the target page in afs_write_begin() when it fails. Fixes: 15b4650e55e0 ("afs: convert to new aops") Signed-off-by: David Howells <dhowells@redhat.com> cc: Nick Piggin <npiggin@gmail.com>
* afs: Fix to take ref on page when PG_private is setDavid Howells2020-10-291-8/+10
| | | | | | | | | | | | | | | | | Fix afs to take a ref on a page when it sets PG_private on it and to drop the ref when removing the flag. Note that in afs_write_begin(), a lot of the time, PG_private is already set on a page to which we're going to add some data. In such a case, we leave the bit set and mustn't increment the page count. As suggested by Matthew Wilcox, use attach/detach_page_private() where possible. Fixes: 31143d5d515e ("AFS: implement basic file write support") Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
* afs: Fix afs_launder_page to not clear PG_writebackDavid Howells2020-10-271-4/+6
| | | | | | | | Fix afs_launder_page() to not clear PG_writeback on the page it is laundering as the flag isn't set in this case. Fixes: 4343d00872e1 ("afs: Get rid of the afs_writeback record") Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Fix deadlock between writeback and truncateDavid Howells2020-10-081-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The afs filesystem has a lock[*] that it uses to serialise I/O operations going to the server (vnode->io_lock), as the server will only perform one modification operation at a time on any given file or directory. This prevents the the filesystem from filling up all the call slots to a server with calls that aren't going to be executed in parallel anyway, thereby allowing operations on other files to obtain slots. [*] Note that is probably redundant for directories at least since i_rwsem is used to serialise directory modifications and lookup/reading vs modification. The server does allow parallel non-modification ops, however. When a file truncation op completes, we truncate the in-memory copy of the file to match - but we do it whilst still holding the io_lock, the idea being to prevent races with other operations. However, if writeback starts in a worker thread simultaneously with truncation (whilst notify_change() is called with i_rwsem locked, writeback pays it no heed), it may manage to set PG_writeback bits on the pages that will get truncated before afs_setattr_success() manages to call truncate_pagecache(). Truncate will then wait for those pages - whilst still inside io_lock: # cat /proc/8837/stack [<0>] wait_on_page_bit_common+0x184/0x1e7 [<0>] truncate_inode_pages_range+0x37f/0x3eb [<0>] truncate_pagecache+0x3c/0x53 [<0>] afs_setattr_success+0x4d/0x6e [<0>] afs_wait_for_operation+0xd8/0x169 [<0>] afs_do_sync_operation+0x16/0x1f [<0>] afs_setattr+0x1fb/0x25d [<0>] notify_change+0x2cf/0x3c4 [<0>] do_truncate+0x7f/0xb2 [<0>] do_sys_ftruncate+0xd1/0x104 [<0>] do_syscall_64+0x2d/0x3a [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 The writeback operation, however, stalls indefinitely because it needs to get the io_lock to proceed: # cat /proc/5940/stack [<0>] afs_get_io_locks+0x58/0x1ae [<0>] afs_begin_vnode_operation+0xc7/0xd1 [<0>] afs_store_data+0x1b2/0x2a3 [<0>] afs_write_back_from_locked_page+0x418/0x57c [<0>] afs_writepages_region+0x196/0x224 [<0>] afs_writepages+0x74/0x156 [<0>] do_writepages+0x2d/0x56 [<0>] __writeback_single_inode+0x84/0x207 [<0>] writeback_sb_inodes+0x238/0x3cf [<0>] __writeback_inodes_wb+0x68/0x9f [<0>] wb_writeback+0x145/0x26c [<0>] wb_do_writeback+0x16a/0x194 [<0>] wb_workfn+0x74/0x177 [<0>] process_one_work+0x174/0x264 [<0>] worker_thread+0x117/0x1b9 [<0>] kthread+0xec/0xf1 [<0>] ret_from_fork+0x1f/0x30 and thus deadlock has occurred. Note that whilst afs_setattr() calls filemap_write_and_wait(), the fact that the caller is holding i_rwsem doesn't preclude more pages being dirtied through an mmap'd region. Fix this by: (1) Use the vnode validate_lock to mediate access between afs_setattr() and afs_writepages(): (a) Exclusively lock validate_lock in afs_setattr() around the whole RPC operation. (b) If WB_SYNC_ALL isn't set on entry to afs_writepages(), trying to shared-lock validate_lock and returning immediately if we couldn't get it. (c) If WB_SYNC_ALL is set, wait for the lock. The validate_lock is also used to validate a file and to zap its cache if the file was altered by a third party, so it's probably a good fit for this. (2) Move the truncation outside of the io_lock in setattr, using the same hook as is used for local directory editing. This requires the old i_size to be retained in the operation record as we commit the revised status to the inode members inside the io_lock still, but we still need to know if we reduced the file size. Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation") Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva2020-08-231-1/+1
| | | | | | | | | | Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
* afs: Fix interruption of operationsDavid Howells2020-07-151-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The afs filesystem driver allows unstarted operations to be cancelled by signal, but most of these can easily be restarted (mkdir for example). The primary culprits for reproducing this are those applications that use SIGALRM to display a progress counter. File lock-extension operation is marked uninterruptible as we have a limited time in which to do it, and the release op is marked uninterruptible also as if we fail to unlock a file, we'll have to wait 20 mins before anyone can lock it again. The store operation logs a warning if it gets interruption, e.g.: kAFS: Unexpected error from FS.StoreData -4 because it's run from the background - but it can also be run from fdatasync()-type things. However, store options aren't marked interruptible at the moment. Fix this in the following ways: (1) Mark store operations as uninterruptible. It might make sense to relax this for certain situations, but I'm not sure how to make sure that background store ops aren't affected by signals to foreground processes that happen to trigger them. (2) In afs_get_io_locks(), where we're getting the serialisation lock for talking to the fileserver, return ERESTARTSYS rather than EINTR because a lot of the operations (e.g. mkdir) are restartable if we haven't yet started sending the op to the server. Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept") Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* afs: Fix truncation issues and mmap writeback sizeDavid Howells2020-06-151-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix the following issues: (1) Fix writeback to reduce the size of a store operation to i_size, effectively discarding the extra data. The problem comes when afs_page_mkwrite() records that a page is about to be modified by mmap(). It doesn't know what bits of the page are going to be modified, so it records the whole page as being dirty (this is stored in page->private as start and end offsets). Without this, the marshalling for the store to the server extends the size of the file to the end of the page (in afs_fs_store_data() and yfs_fs_store_data()). (2) Fix setattr to actually truncate the pagecache, thereby clearing the discarded part of a file. (3) Fix setattr to check that the new size is okay and to disable ATTR_SIZE if i_size wouldn't change. (4) Force i_size to be updated as the result of a truncate. (5) Don't truncate if ATTR_SIZE is not set. (6) Call pagecache_isize_extended() if the file was enlarged. Note that truncate_set_size() isn't used because the setting of i_size is done inside afs_vnode_commit_status() under the vnode->cb_lock. Found with the generic/029 and generic/393 xfstests. Fixes: 31143d5d515e ("AFS: implement basic file write support") Fixes: 4343d00872e1 ("afs: Get rid of the afs_writeback record") Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Concoct ctimesDavid Howells2020-06-151-0/+1
| | | | | | | | | | | | | | | | | | | | | | The in-kernel afs filesystem ignores ctime because the AFS fileserver protocol doesn't support ctimes. This, however, causes various xfstests to fail. Work around this by: (1) Setting ctime to attr->ia_ctime in afs_setattr(). (2) Not ignoring ATTR_MTIME_SET, ATTR_TIMES_SET and ATTR_TOUCH settings. (3) Setting the ctime from the server mtime when on the target file when creating a hard link to it. (4) Setting the ctime on directories from their revised mtimes when renaming/moving a file. Found by the generic/221 and generic/309 xfstests. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: afs_write_end() should change i_size under the right lockDavid Howells2020-06-151-2/+2
| | | | | | | | | | | | Fix afs_write_end() to change i_size under vnode->cb_lock rather than ->wb_lock so that it doesn't race with afs_vnode_commit_status() and afs_getattr(). The ->wb_lock is only meant to guard access to ->wb_keys which isn't accessed by that piece of code. Fixes: 4343d00872e1 ("afs: Get rid of the afs_writeback record") Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Fix non-setting of mtime when writing into mmapDavid Howells2020-06-151-0/+1
| | | | | | | | | | | | | The mtime on an inode needs to be updated when a write is made into an mmap'ed section. There are three ways in which this could be done: update it when page_mkwrite is called, update it when a page is changed from dirty to writeback or leave it to the server and fix the mtime up from the reply to the StoreData RPC. Found with the generic/215 xfstest. Fixes: 1cf7a1518aef ("afs: Implement shared-writeable mmap") Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Fix afs_store_data() to set mtime in new operation descriptorDavid Howells2020-06-111-0/+1
| | | | | | | | | | | Fix afs_store_data() so that it sets the mtime in the new operation descriptor otherwise the mtime on the server gets set to 0 when a write is stored to the server. Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept") Reported-by: Dave Botsch <botsch@cnf.cornell.edu> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* afs: Build an abstraction around an "operation" conceptDavid Howells2020-06-041-58/+90
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Turn the afs_operation struct into the main way that most fileserver operations are managed. Various things are added to the struct, including the following: (1) All the parameters and results of the relevant operations are moved into it, removing corresponding fields from the afs_call struct. afs_call gets a pointer to the op. (2) The target volume is made the main focus of the operation, rather than the target vnode(s), and a bunch of op->vnode->volume are made op->volume instead. (3) Two vnode records are defined (op->file[]) for the vnode(s) involved in most operations. The vnode record (struct afs_vnode_param) contains: - The vnode pointer. - The fid of the vnode to be included in the parameters or that was returned in the reply (eg. FS.MakeDir). - The status and callback information that may be returned in the reply about the vnode. - Callback break and data version tracking for detecting simultaneous third-parth changes. (4) Pointers to dentries to be updated with new inodes. (5) An operations table pointer. The table includes pointers to functions for issuing AFS and YFS-variant RPCs, handling the success and abort of an operation and handling post-I/O-lock local editing of a directory. To make this work, the following function restructuring is made: (A) The rotation loop that issues calls to fileservers that can be found in each function that wants to issue an RPC (such as afs_mkdir()) is extracted out into common code, in a new file called fs_operation.c. (B) The rotation loops, such as the one in afs_mkdir(), are replaced with a much smaller piece of code that allocates an operation, sets the parameters and then calls out to the common code to do the actual work. (C) The code for handling the success and failure of an operation are moved into operation functions (as (5) above) and these are called from the core code at appropriate times. (D) The pseudo inode getting stuff used by the dynamic root code is moved over into dynroot.c. (E) struct afs_iget_data is absorbed into the operation struct and afs_iget() expects to be given an op pointer and a vnode record. (F) Point (E) doesn't work for the root dir of a volume, but we know the FID in advance (it's always vnode 1, unique 1), so a separate inode getter, afs_root_iget(), is provided to special-case that. (G) The inode status init/update functions now also take an op and a vnode record. (H) The RPC marshalling functions now, for the most part, just take an afs_operation struct as their only argument. All the data they need is held there. The result delivery functions write their answers there as well. (I) The call is attached to the operation and then the operation core does the waiting. And then the new operation code is, for the moment, made to just initialise the operation, get the appropriate vnode I/O locks and do the same rotation loop as before. This lays the foundation for the following changes in the future: (*) Overhauling the rotation (again). (*) Support for asynchronous I/O, where the fileserver rotation must be done asynchronously also. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Rename struct afs_fs_cursor to afs_operationDavid Howells2020-05-311-1/+1
| | | | | | | | | | As a prelude to implementing asynchronous fileserver operations in the afs filesystem, rename struct afs_fs_cursor to afs_operation. This struct is going to form the core of the operation management and is going to acquire more members in later. Signed-off-by: David Howells <dhowells@redhat.com>
* Merge tag 'afs-next-20190628' of ↵Linus Torvalds2019-07-101-2/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull afs updates from David Howells: "A set of minor changes for AFS: - Remove an unnecessary check in afs_unlink() - Add a tracepoint for tracking callback management - Add a tracepoint for afs_server object usage - Use struct_size() - Add mappings for AFS UAE abort codes to Linux error codes, using symbolic names rather than hex numbers in the .c file" * tag 'afs-next-20190628' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: afs: Add support for the UAE error table fs/afs: use struct_size() in kzalloc() afs: Trace afs_server usage afs: Add some callback management tracepoints afs: afs_unlink() doesn't need to check dentry->d_inode
| * fs/afs: use struct_size() in kzalloc()Zhengyuan Liu2019-06-201-2/+1
| | | | | | | | | | | | | | | | | | As Gustavo said in other patches doing the same replace, we can now use the new struct_size() helper to avoid leaving these open-coded and prone to type mistake. Signed-off-by: Zhengyuan Liu <liuzhengyuan@kylinos.cn> Signed-off-by: David Howells <dhowells@redhat.com>
* | treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152Thomas Gleixner2019-05-301-5/+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 as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* afs: Fix application of status and callback to be under same lockDavid Howells2019-05-161-43/+55
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When applying the status and callback in the response of an operation, apply them in the same critical section so that there's no race between checking the callback state and checking status-dependent state (such as the data version). Fix this by: (1) Allocating a joint {status,callback} record (afs_status_cb) before calling the RPC function for each vnode for which the RPC reply contains a status or a status plus a callback. A flag is set in the record to indicate if a callback was actually received. (2) These records are passed into the RPC functions to be filled in. The afs_decode_status() and yfs_decode_status() functions are removed and the cb_lock is no longer taken. (3) xdr_decode_AFSFetchStatus() and xdr_decode_YFSFetchStatus() no longer update the vnode. (4) xdr_decode_AFSCallBack() and xdr_decode_YFSCallBack() no longer update the vnode. (5) vnodes, expected data-version numbers and callback break counters (cb_break) no longer need to be passed to the reply delivery functions. Note that, for the moment, the file locking functions still need access to both the call and the vnode at the same time. (6) afs_vnode_commit_status() is now given the cb_break value and the expected data_version and the task of applying the status and the callback to the vnode are now done here. This is done under a single taking of vnode->cb_lock. (7) afs_pages_written_back() is now called by afs_store_data() rather than by the reply delivery function. afs_pages_written_back() has been moved to before the call point and is now given the first and last page numbers rather than a pointer to the call. (8) The indicator from YFS.RemoveFile2 as to whether the target file actually got removed (status.abort_code == VNOVNODE) rather than merely dropping a link is now checked in afs_unlink rather than in xdr_decode_YFSFetchStatus(). Supplementary fixes: (*) afs_cache_permit() now gets the caller_access mask from the afs_status_cb object rather than picking it out of the vnode's status record. afs_fetch_status() returns caller_access through its argument list for this purpose also. (*) afs_inode_init_from_status() now uses a write lock on cb_lock rather than a read lock and now sets the callback inside the same critical section. Fixes: c435ee34551e ("afs: Overhaul the callback handling") Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Make some RPC operations non-interruptibleDavid Howells2019-05-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make certain RPC operations non-interruptible, including: (*) Set attributes (*) Store data We don't want to get interrupted during a flush on close, flush on unlock, writeback or an inode update, leaving us in a state where we still need to do the writeback or update. (*) Extend lock (*) Release lock We don't want to get lock extension interrupted as the file locks on the server are time-limited. Interruption during lock release is less of an issue since the lock is time-limited, but it's better to complete the release to avoid a several-minute wait to recover it. *Setting* the lock isn't a problem if it's interrupted since we can just return to the user and tell them they were interrupted - at which point they can elect to retry. (*) Silly unlink We want to remove silly unlink files if we can, rather than leaving them for the salvager to clear up. Note that whilst these calls are no longer interruptible, they do have timeouts on them, so if the server stops responding the call will fail with something like ETIME or ECONNRESET. Without this, the following: kAFS: Unexpected error from FS.StoreData -512 appears in dmesg when a pending store data gets interrupted and some processes may just hang. Additionally, make the code that checks/updates the server record ignore failure due to interruption if the main call is uninterruptible and if the server has an address list. The next op will check it again since the expiration time on the old list has past. Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation") Reported-by: Jonathan Billings <jsbillings@jsbillings.org> Reported-by: Marc Dionne <marc.dionne@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Unlock pages for __pagevec_release()Marc Dionne2019-04-131-0/+1
| | | | | | | | | | | | __pagevec_release() complains loudly if any page in the vector is still locked. The pages need to be locked for generic_error_remove_page(), but that function doesn't actually unlock them. Unlock the pages afterwards. Signed-off-by: Marc Dionne <marc.dionne@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Jonathan Billings <jsbillin@umich.edu>
* afs: Increase to 64-bit volume ID and 96-bit vnode ID for YFSDavid Howells2018-10-241-9/+9
| | | | | | | | | | | | | | Increase the sizes of the volume ID to 64 bits and the vnode ID (inode number equivalent) to 96 bits to allow the support of YFS. This requires the iget comparator to check the vnode->fid rather than i_ino and i_generation as i_ino is not sufficiently capacious. It also requires this data to be placed into the vnode cache key for fscache. For the moment, just discard the top 32 bits of the vnode ID when returning it though stat. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Don't invoke the server to read data beyond EOFDavid Howells2018-10-241-0/+11
| | | | | | | When writing a new page, clear space in the page rather than attempting to load it from the server if the space is beyond the EOF. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Add a couple of tracepoints to log I/O errorsDavid Howells2018-10-241-0/+1
| | | | | | | Add a couple of tracepoints to log the production of I/O errors within the AFS filesystem. Signed-off-by: David Howells <dhowells@redhat.com>
* fs/afs: use new return type vm_fault_tSouptick Joarder2018-08-231-1/+1
| | | | | | | | | | | | | | | | | Use new return type vm_fault_t for fault handler in struct vm_operations_struct. For now, this is just documenting that the function returns a VM_FAULT value rather than an errno. Once all instances are converted, vm_fault_t will become a distinct type. See 1c8f422059ae ("mm: change return type to vm_fault_t") for reference. Link: http://lkml.kernel.org/r/20180702152017.GA3780@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* afs: Fix whole-volume callback handlingDavid Howells2018-05-141-1/+1
| | | | | | | | | | | | | It's possible for an AFS file server to issue a whole-volume notification that callbacks on all the vnodes in the file have been broken. This is done for R/O and backup volumes (which don't have per-file callbacks) and for things like a volume being taken offline. Fix callback handling to detect whole-volume notifications, to track it across operations and to check it during inode validation. Fixes: c435ee34551e ("afs: Overhaul the callback handling") Signed-off-by: David Howells <dhowells@redhat.com>
* Merge branch 'afs-dh' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds2018-04-121-20/+21
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull AFS updates from Al Viro: "The AFS series posted by dhowells depended upon lookup_one_len() rework; now that prereq is in the mainline, that series had been rebased on top of it and got some exposure and testing..." * 'afs-dh' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: afs: Do better accretion of small writes on newly created content afs: Add stats for data transfer operations afs: Trace protocol errors afs: Locally edit directory data for mkdir/create/unlink/... afs: Adjust the directory XDR structures afs: Split the directory content defs into a header afs: Fix directory handling afs: Split the dynroot stuff out and give it its own ops tables afs: Keep track of invalid-before version for dentry coherency afs: Rearrange status mapping afs: Make it possible to get the data version in readpage afs: Init inode before accessing cache afs: Introduce a statistics proc file afs: Dump bad status record afs: Implement @cell substitution handling afs: Implement @sys substitution handling afs: Prospectively look up extra files when doing a single lookup afs: Don't over-increment the cell usage count when pinning it afs: Fix checker warnings vfs: Remove the const from dir_context::actor
| * afs: Do better accretion of small writes on newly created contentDavid Howells2018-04-091-19/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Processes like ld that do lots of small writes that aren't necessarily contiguous result in a lot of small StoreData operations to the server, the idea being that if someone else changes the data on the server, we only write our changes over that and not the space between. Further, we don't want to write back empty space if we can avoid it to make it easier for the server to do sparse files. However, making lots of tiny RPC ops is a lot less efficient for the server than one big one because each op requires allocation of resources and the taking of locks, so we want to compromise a bit. Reduce the load by the following: (1) If a file is just created locally or has just been truncated with O_TRUNC locally, allow subsequent writes to the file to be merged with intervening space if that space doesn't cross an entire intervening page. (2) Don't flush the file on ->flush() but rather on ->release() if the file was open for writing. Just linking vmlinux.o, without this patch, looking in /proc/fs/afs/stats: file-wr : n=441 nb=513581204 and after the patch: file-wr : n=62 nb=513668555 there were 379 fewer StoreData RPC operations at the expense of an extra 87K being written. Signed-off-by: David Howells <dhowells@redhat.com>
| * afs: Add stats for data transfer operationsDavid Howells2018-04-091-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add statistics to /proc/fs/afs/stats for data transfer RPC operations. New lines are added that look like: file-rd : n=55794 nb=10252282150 file-wr : n=9789 nb=3247763645 where n= indicates the number of ops completed and nb= indicates the number of bytes successfully transferred. file-rd is the counts for read/fetch operations and file-wr the counts for write/store operations. Note that directory and symlink downloading are included in the file-rd stats at the moment. Signed-off-by: David Howells <dhowells@redhat.com>
| * afs: Fix directory handlingDavid Howells2018-04-091-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | AFS directories are structured blobs that are downloaded just like files and then parsed by the lookup and readdir code and, as such, are currently handled in the pagecache like any other file, with the entire directory content being thrown away each time the directory changes. However, since the blob is a known structure and since the data version counter on a directory increases by exactly one for each change committed to that directory, we can actually edit the directory locally rather than fetching it from the server after each locally-induced change. What we can't do, though, is mix data from the server and data from the client since the server is technically at liberty to rearrange or compress a directory if it sees fit, provided it updates the data version number when it does so and breaks the callback (ie. sends a notification). Further, lookup with lookup-ahead, readdir and, when it arrives, local editing are likely want to scan the whole of a directory. So directory handling needs to be improved to maintain the coherency of the directory blob prior to permitting local directory editing. To this end: (1) If any directory page gets discarded, invalidate and reread the entire directory. (2) If readpage notes that if when it fetches a single page that the version number has changed, the entire directory is flagged for invalidation. (3) Read as much of the directory in one go as we can. Note that this removes local caching of directories in fscache for the moment as we can't pass the pages to fscache_read_or_alloc_pages() since page->lru is in use by the LRU. Signed-off-by: David Howells <dhowells@redhat.com>
* | page cache: use xa_lockMatthew Wilcox2018-04-111-4/+5
|/ | | | | | | | | | | | | | | | | Remove the address_space ->tree_lock and use the xa_lock newly added to the radix_tree_root. Rename the address_space ->page_tree to ->i_pages, since we don't really care that it's a tree. [willy@infradead.org: fix nds32, fs/dax.c] Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Jeff Layton <jlayton@redhat.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* afs: Fix missing error handling in afs_write_end()David Howells2018-01-021-3/+5
| | | | | | | afs_write_end() is missing page unlock and put if afs_fill_page() fails. Reported-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Make afs_write_begin() avoid writing to a page that's being storedDavid Howells2017-11-241-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make afs_write_begin() wait for a page that's marked PG_writeback because: (1) We need to avoid interference with the data being stored so that the data on the server ends up in a defined state. (2) page->private is used to track the window of dirty data within a page, but it's also used by the storage code to track what's being written, being cleared by the completion notification. Ownership can't be relinquished by the storage code until completion because it a store fails, the data must be remarked dirty. Tracing shows something like the following (edited): x86_64-linux-gn-15940 [1] afs_page_dirty: vn=ffff8800bef33800 9c75 begin 0-125 kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 store+ 0-125 x86_64-linux-gn-15940 [1] afs_page_dirty: vn=ffff8800bef33800 9c75 begin 0-2052 kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 clear 0-2052 kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 store 0-0 kworker/u8:3-114 [2] afs_page_dirty: vn=ffff8800bef33800 9c75 WARN 0-0 The clear (completion) corresponding to the store+ (store continuation from a previous page) happens between the second begin (afs_write_begin) and the store corresponding to that. This results in the second store not seeing any data to write back, leading to the following warning: WARNING: CPU: 2 PID: 114 at ../fs/afs/write.c:403 afs_write_back_from_locked_page+0x19d/0x76c [kafs] Modules linked in: kafs(E) CPU: 2 PID: 114 Comm: kworker/u8:3 Tainted: G E 4.14.0-fscache+ #242 Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Workqueue: writeback wb_workfn (flush-afs-2) task: ffff8800cad72600 task.stack: ffff8800cad44000 RIP: 0010:afs_write_back_from_locked_page+0x19d/0x76c [kafs] RSP: 0018:ffff8800cad47aa0 EFLAGS: 00010246 RAX: 0000000000000001 RBX: ffff8800bef33a20 RCX: 0000000000000000 RDX: 000000000000000f RSI: ffffffff81c5d0e0 RDI: ffff8800cad72e78 RBP: ffff8800d31ea1e8 R08: ffff8800c1358000 R09: ffff8800ca00e400 R10: ffff8800cad47a38 R11: ffff8800c5d9e400 R12: 0000000000000000 R13: ffffea0002d9df00 R14: ffffffffa0023c1c R15: 0000000000007fdf FS: 0000000000000000(0000) GS:ffff8800ca700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f85ac6c4000 CR3: 0000000001c10001 CR4: 00000000001606e0 Call Trace: ? clear_page_dirty_for_io+0x23a/0x267 afs_writepages_region+0x1be/0x286 [kafs] afs_writepages+0x60/0x127 [kafs] do_writepages+0x36/0x70 __writeback_single_inode+0x12f/0x635 writeback_sb_inodes+0x2cc/0x452 __writeback_inodes_wb+0x68/0x9f wb_writeback+0x208/0x470 ? wb_workfn+0x22b/0x565 wb_workfn+0x22b/0x565 ? worker_thread+0x230/0x2ac process_one_work+0x2cc/0x517 ? worker_thread+0x230/0x2ac worker_thread+0x1d4/0x2ac ? rescuer_thread+0x29b/0x29b kthread+0x15d/0x165 ? kthread_create_on_node+0x3f/0x3f ? call_usermodehelper_exec_async+0x118/0x11f ret_from_fork+0x24/0x30 Signed-off-by: David Howells <dhowells@redhat.com>
* Merge tag 'afs-next-20171113' of ↵Linus Torvalds2017-11-161-322/+387
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull AFS updates from David Howells: "kAFS filesystem driver overhaul. The major points of the overhaul are: (1) Preliminary groundwork is laid for supporting network-namespacing of kAFS. The remainder of the namespacing work requires some way to pass namespace information to submounts triggered by an automount. This requires something like the mount overhaul that's in progress. (2) sockaddr_rxrpc is used in preference to in_addr for holding addresses internally and add support for talking to the YFS VL server. With this, kAFS can do everything over IPv6 as well as IPv4 if it's talking to servers that support it. (3) Callback handling is overhauled to be generally passive rather than active. 'Callbacks' are promises by the server to tell us about data and metadata changes. Callbacks are now checked when we next touch an inode rather than actively going and looking for it where possible. (4) File access permit caching is overhauled to store the caching information per-inode rather than per-directory, shared over subordinate files. Whilst older AFS servers only allow ACLs on directories (shared to the files in that directory), newer AFS servers break that restriction. To improve memory usage and to make it easier to do mass-key removal, permit combinations are cached and shared. (5) Cell database management is overhauled to allow lighter locks to be used and to make cell records autonomous state machines that look after getting their own DNS records and cleaning themselves up, in particular preventing races in acquiring and relinquishing the fscache token for the cell. (6) Volume caching is overhauled. The afs_vlocation record is got rid of to simplify things and the superblock is now keyed on the cell and the numeric volume ID only. The volume record is tied to a superblock and normal superblock management is used to mediate the lifetime of the volume fscache token. (7) File server record caching is overhauled to make server records independent of cells and volumes. A server can be in multiple cells (in such a case, the administrator must make sure that the VL services for all cells correctly reflect the volumes shared between those cells). Server records are now indexed using the UUID of the server rather than the address since a server can have multiple addresses. (8) File server rotation is overhauled to handle VMOVED, VBUSY (and similar), VOFFLINE and VNOVOL indications and to handle rotation both of servers and addresses of those servers. The rotation will also wait and retry if the server says it is busy. (9) Data writeback is overhauled. Each inode no longer stores a list of modified sections tagged with the key that authorised it in favour of noting the modified region of a page in page->private and storing a list of keys that made modifications in the inode. This simplifies things and allows other keys to be used to actually write to the server if a key that made a modification becomes useless. (10) Writable mmap() is implemented. This allows a kernel to be build entirely on AFS. Note that Pre AFS-3.4 servers are no longer supported, though this can be added back if necessary (AFS-3.4 was released in 1998)" * tag 'afs-next-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (35 commits) afs: Protect call->state changes against signals afs: Trace page dirty/clean afs: Implement shared-writeable mmap afs: Get rid of the afs_writeback record afs: Introduce a file-private data record afs: Use a dynamic port if 7001 is in use afs: Fix directory read/modify race afs: Trace the sending of pages afs: Trace the initiation and completion of client calls afs: Fix documentation on # vs % prefix in mount source specification afs: Fix total-length calculation for multiple-page send afs: Only progress call state at end of Tx phase from rxrpc callback afs: Make use of the YFS service upgrade to fully support IPv6 afs: Overhaul volume and server record caching and fileserver rotation afs: Move server rotation code into its own file afs: Add an address list concept afs: Overhaul cell database management afs: Overhaul permit caching afs: Overhaul the callback handling afs: Rename struct afs_call server member to cm_server ...
| * afs: Trace page dirty/cleanDavid Howells2017-11-131-13/+21
| | | | | | | | | | | | | | Add a trace event that logs the dirtying and cleaning of pages attached to AFS inodes. Signed-off-by: David Howells <dhowells@redhat.com>
| * afs: Implement shared-writeable mmapDavid Howells2017-11-131-8/+32
| | | | | | | | | | | | Implement shared-writeable mmap for AFS. Signed-off-by: David Howells <dhowells@redhat.com>
| * afs: Get rid of the afs_writeback recordDavid Howells2017-11-131-317/+316
| | | | | | | | | | | | | | | | | | | | Get rid of the afs_writeback record that kAFS is using to match keys with writes made by that key. Instead, keep a list of keys that have a file open for writing and/or sync'ing and iterate through those. Signed-off-by: David Howells <dhowells@redhat.com>
| * afs: Introduce a file-private data recordDavid Howells2017-11-131-2/+2
| | | | | | | | | | | | | | Introduce a file-private data record for kAFS and put the key into it rather than storing the key in file->private_data. Signed-off-by: David Howells <dhowells@redhat.com>
| * afs: Overhaul volume and server record caching and fileserver rotationDavid Howells2017-11-131-2/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current code assumes that volumes and servers are per-cell and are never shared, but this is not enforced, and, indeed, public cells do exist that are aliases of each other. Further, an organisation can, say, set up a public cell and a private cell with overlapping, but not identical, sets of servers. The difference is purely in the database attached to the VL servers. The current code will malfunction if it sees a server in two cells as it assumes global address -> server record mappings and that each server is in just one cell. Further, each server may have multiple addresses - and may have addresses of different families (IPv4 and IPv6, say). To this end, the following structural changes are made: (1) Server record management is overhauled: (a) Server records are made independent of cell. The namespace keeps track of them, volume records have lists of them and each vnode has a server on which its callback interest currently resides. (b) The cell record no longer keeps a list of servers known to be in that cell. (c) The server records are now kept in a flat list because there's no single address to sort on. (d) Server records are now keyed by their UUID within the namespace. (e) The addresses for a server are obtained with the VL.GetAddrsU rather than with VL.GetEntryByName, using the server's UUID as a parameter. (f) Cached server records are garbage collected after a period of non-use and are counted out of existence before purging is allowed to complete. This protects the work functions against rmmod. (g) The servers list is now in /proc/fs/afs/servers. (2) Volume record management is overhauled: (a) An RCU-replaceable server list is introduced. This tracks both servers and their coresponding callback interests. (b) The superblock is now keyed on cell record and numeric volume ID. (c) The volume record is now tied to the superblock which mounts it, and is activated when mounted and deactivated when unmounted. This makes it easier to handle the cache cookie without causing a double-use in fscache. (d) The volume record is loaded from the VLDB using VL.GetEntryByNameU to get the server UUID list. (e) The volume name is updated if it is seen to have changed when the volume is updated (the update is keyed on the volume ID). (3) The vlocation record is got rid of and VLDB records are no longer cached. Sufficient information is stored in the volume record, though an update to a volume record is now no longer shared between related volumes (volumes come in bundles of three: R/W, R/O and backup). and the following procedural changes are made: (1) The fileserver cursor introduced previously is now fleshed out and used to iterate over fileservers and their addresses. (2) Volume status is checked during iteration, and the server list is replaced if a change is detected. (3) Server status is checked during iteration, and the address list is replaced if a change is detected. (4) The abort code is saved into the address list cursor and -ECONNABORTED returned in afs_make_call() if a remote abort happened rather than translating the abort into an error message. This allows actions to be taken depending on the abort code more easily. (a) If a VMOVED abort is seen then this is handled by rechecking the volume and restarting the iteration. (b) If a VBUSY, VRESTARTING or VSALVAGING abort is seen then this is handled by sleeping for a short period and retrying and/or trying other servers that might serve that volume. A message is also displayed once until the condition has cleared. (c) If a VOFFLINE abort is seen, then this is handled as VBUSY for the moment. (d) If a VNOVOL abort is seen, the volume is rechecked in the VLDB to see if it has been deleted; if not, the fileserver is probably indicating that the volume couldn't be attached and needs salvaging. (e) If statfs() sees one of these aborts, it does not sleep, but rather returns an error, so as not to block the umount program. (5) The fileserver iteration functions in vnode.c are now merged into their callers and more heavily macroised around the cursor. vnode.c is removed. (6) Operations on a particular vnode are serialised on that vnode because the server will lock that vnode whilst it operates on it, so a second op sent will just have to wait. (7) Fileservers are probed with FS.GetCapabilities before being used. This is where service upgrade will be done. (8) A callback interest on a fileserver is set up before an FS operation is performed and passed through to afs_make_call() so that it can be set on the vnode if the operation returns a callback. The callback interest is passed through to afs_iget() also so that it can be set there too. In general, record updating is done on an as-needed basis when we try to access servers, volumes or vnodes rather than offloading it to work items and special threads. Notes: (1) Pre AFS-3.4 servers are no longer supported, though this can be added back if necessary (AFS-3.4 was released in 1998). (2) VBUSY is retried forever for the moment at intervals of 1s. (3) /proc/fs/afs/<cell>/servers no longer exists. Signed-off-by: David Howells <dhowells@redhat.com>
* | mm, pagevec: remove cold parameter for pagevecsMel Gorman2017-11-151-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Every pagevec_init user claims the pages being released are hot even in cases where it is unlikely the pages are hot. As no one cares about the hotness of pages being released to the allocator, just ditch the parameter. No performance impact is expected as the overhead is marginal. The parameter is removed simply because it is a bit stupid to have a useless parameter copied everywhere. Link: http://lkml.kernel.org/r/20171018075952.10627-6-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | afs: use find_get_pages_range_tag()Jan Kara2017-11-151-9/+2
|/ | | | | | | | | | | | | Use find_get_pages_range_tag() in afs_writepages_region() as we are interested only in pages from given range. Remove unnecessary code after this conversion. Link: http://lkml.kernel.org/r/20171009151359.31984-16-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: convert a pile of fsync routines to errseq_t based reportingJeff Layton2017-08-011-1/+1
| | | | | | | | | | | | | | | | | | | This patch converts most of the in-kernel filesystems that do writeback out of the pagecache to report errors using the errseq_t-based infrastructure that was recently added. This allows them to report errors once for each open file description. Most filesystems have a fairly straightforward fsync operation. They call filemap_write_and_wait_range to write back all of the data and wait on it, and then (sometimes) sync out the metadata. For those filesystems this is a straightforward conversion from calling filemap_write_and_wait_range in their fsync operation to calling file_write_and_wait_range. Acked-by: Jan Kara <jack@suse.cz> Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com> Signed-off-by: Jeff Layton <jlayton@redhat.com>
* afs: Don't wait for page writeback with the page lock heldDavid Howells2017-03-161-5/+4
| | | | | | Drop the page lock before waiting for page writeback. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: ->writepage() shouldn't call clear_page_dirty_for_io()David Howells2017-03-161-3/+3
| | | | | | | | | | | The ->writepage() op shouldn't call clear_page_dirty_for_io() as that has already been called by the caller. Fix afs_writepage() by moving the call out of afs_write_back_from_locked_page() to afs_writepages_region() where it is needed. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Fix afs_kill_pages()David Howells2017-03-161-3/+7
| | | | | | | | | | | | | | | | | | | | Fix afs_kill_pages() in two ways: (1) If a writeback has been partially flushed, then if we try and kill the pages it contains, some of them may no longer be undergoing writeback and end_page_writeback() will assert. Fix this by checking to see whether the page in question is actually undergoing writeback before ending that writeback. (2) The loop that scans for pages to kill doesn't increase the first page index, and so the loop may not terminate, but it will try to process the same pages over and over again. Fix this by increasing the first page index to one after the last page we processed. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Fix page leak in afs_write_begin()David Howells2017-03-161-2/+5
| | | | | | | afs_write_begin() leaks a ref and a lock on a page if afs_fill_page() fails. Fix the leak by unlocking and releasing the page in the error path. Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Flush outstanding writes when an fd is closedDavid Howells2017-03-161-0/+14
| | | | | | | | Flush outstanding writes in afs when an fd is closed. This is what NFS and CIFS do. Reported-by: Marc Dionne <marc.c.dionne@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Handle a short write to an AFS pageDavid Howells2017-03-161-9/+19
| | | | | | | | | | | | Handle the situation where afs_write_begin() is told to expect that a full-page write will be made, but this doesn't happen (EFAULT, CTRL-C, etc.), and so afs_write_end() sees a partial write took place. Currently, no attempt is to deal with the discrepency. Fix this by loading the gap from the server. Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Fix page overput in afs_fill_page()David Howells2017-03-161-0/+1
| | | | | | | | | | | | | | | | | afs_fill_page() loads the page it wants to fill into the afs_read request without incrementing its refcount - but then calls afs_put_read() to clean up afterwards, which then releases a ref on the page. Fix this by getting a ref on the page before calling afs_vnode_fetch_data(). This causes sync after a write to hang in afs_writepages_region() because find_get_pages_tag() gets confused and doesn't return. Fixes: 196ee9cd2d04 ("afs: Make afs_fs_fetch_data() take a list of pages") Reported-by: Marc Dionne <marc.dionne@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Marc Dionne <marc.dionne@auristor.com>
* afs: Fix missing put_page()David Howells2017-03-161-0/+1
| | | | | | | In afs_writepages_region(), inside the loop where we find dirty pages to deal with, one of the if-statements is missing a put_page(). Signed-off-by: David Howells <dhowells@redhat.com>
* afs: Make afs_fs_fetch_data() take a list of pagesDavid Howells2017-01-061-4/+15
| | | | | | | Make afs_fs_fetch_data() take a list of pages for bulk data transfer. This will allow afs_readpages() to be made more efficient. Signed-off-by: David Howells <dhowells@redhat.com>
* fs: use mapping_set_error instead of opencoded set_bitMichal Hocko2016-10-111-3/+2
| | | | | | | | | | | The mapping_set_error() helper sets the correct AS_ flag for the mapping so there is no reason to open code it. Use the helper directly. [akpm@linux-foundation.org: be honest about conversion from -ENXIO to -EIO] Link: http://lkml.kernel.org/r/20160912111608.2588-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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