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authorDavid Howells <dhowells@redhat.com>2017-11-02 18:27:52 +0300
committerDavid Howells <dhowells@redhat.com>2017-11-13 18:38:21 +0300
commit1cf7a1518aefa69ac6ba0c3f9206073e4221e3c8 (patch)
tree17788e9c0e145c336761adedf27460daccc76887 /fs/afs
parent4343d00872e1de9a470d951bf09bdd18bc73f555 (diff)
downloadlinux-1cf7a1518aefa69ac6ba0c3f9206073e4221e3c8.tar.xz
afs: Implement shared-writeable mmap
Implement shared-writeable mmap for AFS. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs')
-rw-r--r--fs/afs/file.c22
-rw-r--r--fs/afs/internal.h1
-rw-r--r--fs/afs/write.c40
3 files changed, 54 insertions, 9 deletions
diff --git a/fs/afs/file.c b/fs/afs/file.c
index c3a7bc1281f5..675c5c268a52 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -19,6 +19,7 @@
#include <linux/task_io_accounting_ops.h>
#include "internal.h"
+static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
static int afs_readpage(struct file *file, struct page *page);
static void afs_invalidatepage(struct page *page, unsigned int offset,
unsigned int length);
@@ -34,7 +35,7 @@ const struct file_operations afs_file_operations = {
.llseek = generic_file_llseek,
.read_iter = generic_file_read_iter,
.write_iter = afs_file_write,
- .mmap = generic_file_readonly_mmap,
+ .mmap = afs_file_mmap,
.splice_read = generic_file_splice_read,
.fsync = afs_fsync,
.lock = afs_lock,
@@ -61,6 +62,12 @@ const struct address_space_operations afs_fs_aops = {
.writepages = afs_writepages,
};
+static const struct vm_operations_struct afs_vm_ops = {
+ .fault = filemap_fault,
+ .map_pages = filemap_map_pages,
+ .page_mkwrite = afs_page_mkwrite,
+};
+
/*
* Discard a pin on a writeback key.
*/
@@ -629,3 +636,16 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
_leave(" = T");
return 1;
}
+
+/*
+ * Handle setting up a memory mapping on an AFS file.
+ */
+static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int ret;
+
+ ret = generic_file_mmap(file, vma);
+ if (ret == 0)
+ vma->vm_ops = &afs_vm_ops;
+ return ret;
+}
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 688562ae3bf8..1de36e6abd5e 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -886,6 +886,7 @@ extern void afs_pages_written_back(struct afs_vnode *, struct afs_call *);
extern ssize_t afs_file_write(struct kiocb *, struct iov_iter *);
extern int afs_flush(struct file *, fl_owner_t);
extern int afs_fsync(struct file *, loff_t, loff_t, int);
+extern int afs_page_mkwrite(struct vm_fault *);
extern void afs_prune_wb_keys(struct afs_vnode *);
extern int afs_launder_page(struct page *);
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 4c131371005b..6807277ef956 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -749,21 +749,45 @@ int afs_flush(struct file *file, fl_owner_t id)
* notification that a previously read-only page is about to become writable
* - if it returns an error, the caller will deliver a bus error signal
*/
-int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+int afs_page_mkwrite(struct vm_fault *vmf)
{
- struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
+ struct file *file = vmf->vma->vm_file;
+ struct inode *inode = file_inode(file);
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ unsigned long priv;
_enter("{{%x:%u}},{%lx}",
- vnode->fid.vid, vnode->fid.vnode, page->index);
+ vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
- /* wait for the page to be written to the cache before we allow it to
- * be modified */
+ sb_start_pagefault(inode->i_sb);
+
+ /* Wait for the page to be written to the cache before we allow it to
+ * be modified. We then assume the entire page will need writing back.
+ */
#ifdef CONFIG_AFS_FSCACHE
- fscache_wait_on_page_write(vnode->cache, page);
+ fscache_wait_on_page_write(vnode->cache, vmf->page);
#endif
- _leave(" = 0");
- return 0;
+ if (PageWriteback(vmf->page) &&
+ wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
+ return VM_FAULT_RETRY;
+
+ if (lock_page_killable(vmf->page) < 0)
+ return VM_FAULT_RETRY;
+
+ /* We mustn't change page->private until writeback is complete as that
+ * details the portion of the page we need to write back and we might
+ * need to redirty the page if there's a problem.
+ */
+ wait_on_page_writeback(vmf->page);
+
+ priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
+ priv |= 0; /* From */
+ SetPagePrivate(vmf->page);
+ set_page_private(vmf->page, priv);
+
+ sb_end_pagefault(inode->i_sb);
+ return VM_FAULT_LOCKED;
}
/*