fs: afs: restore mmap_prepare implementation

Commit 9d5403b1036c ("fs: convert most other generic_file_*mmap() users to
.mmap_prepare()") updated AFS to use the mmap_prepare callback in favour
of the deprecated mmap callback.

However, it did not account for the fact that mmap_prepare is called
pre-merge, and may then be merged, nor that mmap_prepare can fail to map
due to an out of memory error.

This change was therefore since reverted.

Both of those are cases in which we should not be incrementing a reference
count.

With the newly added vm_ops->mapped callback available, we can simply
defer this operation to that callback which is only invoked once the
mapping is successfully in place (but not yet visible to userspace as the
mmap and VMA write locks are held).

This allows us to once again reimplement the .mmap_prepare implementation
for this file system.

Therefore add afs_mapped() to implement this callback for AFS, and remove
the code doing so in afs_mmap_prepare().

Also update afs_vm_open(), afs_vm_close() and afs_vm_map_pages() to be
consistent in how the vnode is accessed.

Link: https://lkml.kernel.org/r/ad9a94350a9c7d2bdab79fc397ef0f64d3412d71.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

authored by

Lorenzo Stoakes (Oracle) and committed by

Andrew Morton 1 month ago 4995c67d fbfc6578

+29 -13

1 changed file

expand all

afs

file.c

+29 -13

fs/afs/file.c

··· 19 19 #include <trace/events/netfs.h> 20 20 #include "internal.h" 21 21 22 - static int afs_file_mmap(struct file *file, struct vm_area_struct *vma); 22 + static int afs_file_mmap_prepare(struct vm_area_desc *desc); 23 23 24 24 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter); 25 25 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos, ··· 28 28 static void afs_vm_open(struct vm_area_struct *area); 29 29 static void afs_vm_close(struct vm_area_struct *area); 30 30 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff); 31 + static int afs_mapped(unsigned long start, unsigned long end, pgoff_t pgoff, 32 + const struct file *file, void **vm_private_data); 31 33 32 34 const struct file_operations afs_file_operations = { 33 35 .open = afs_open, ··· 37 35 .llseek = generic_file_llseek, 38 36 .read_iter = afs_file_read_iter, 39 37 .write_iter = netfs_file_write_iter, 40 - .mmap = afs_file_mmap, 38 + .mmap_prepare = afs_file_mmap_prepare, 41 39 .splice_read = afs_file_splice_read, 42 40 .splice_write = iter_file_splice_write, 43 41 .fsync = afs_fsync, ··· 63 61 }; 64 62 65 63 static const struct vm_operations_struct afs_vm_ops = { 64 + .mapped = afs_mapped, 66 65 .open = afs_vm_open, 67 66 .close = afs_vm_close, 68 67 .fault = filemap_fault, ··· 495 492 /* 496 493 * Handle setting up a memory mapping on an AFS file. 497 494 */ 498 - static int afs_file_mmap(struct file *file, struct vm_area_struct *vma) 495 + static int afs_file_mmap_prepare(struct vm_area_desc *desc) 499 496 { 500 - struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); 501 497 int ret; 502 498 503 - afs_add_open_mmap(vnode); 499 + ret = generic_file_mmap_prepare(desc); 500 + if (ret) 501 + return ret; 504 502 505 - ret = generic_file_mmap(file, vma); 506 - if (ret == 0) 507 - vma->vm_ops = &afs_vm_ops; 508 - else 509 - afs_drop_open_mmap(vnode); 503 + desc->vm_ops = &afs_vm_ops; 510 504 return ret; 505 + } 506 + 507 + static int afs_mapped(unsigned long start, unsigned long end, pgoff_t pgoff, 508 + const struct file *file, void **vm_private_data) 509 + { 510 + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); 511 + 512 + afs_add_open_mmap(vnode); 513 + return 0; 511 514 } 512 515 513 516 static void afs_vm_open(struct vm_area_struct *vma) 514 517 { 515 - afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file))); 518 + struct file *file = vma->vm_file; 519 + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); 520 + 521 + afs_add_open_mmap(vnode); 516 522 } 517 523 518 524 static void afs_vm_close(struct vm_area_struct *vma) 519 525 { 520 - afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file))); 526 + struct file *file = vma->vm_file; 527 + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); 528 + 529 + afs_drop_open_mmap(vnode); 521 530 } 522 531 523 532 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff) 524 533 { 525 - struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file)); 534 + struct file *file = vmf->vma->vm_file; 535 + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); 526 536 527 537 if (afs_check_validity(vnode)) 528 538 return filemap_map_pages(vmf, start_pgoff, end_pgoff);

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