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9p: Convert to using the netfs helper lib to do reads and caching

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Convert the 9p filesystem to use the netfs helper lib to handle readpage,
readahead and write_begin, converting those into a common issue_op for the
filesystem itself to handle.  The netfs helper lib also handles reading
from fscache if a cache is available, and interleaving reads from both
sources.

This change also switches from the old fscache I/O API to the new one,
meaning that fscache no longer keeps track of netfs pages and instead does
async DIO between the backing files and the 9p file pagecache.  As a part
of this change, the handling of PG_fscache changes.  It now just means that
the cache has a write I/O operation in progress on a page (PG_locked
is used for a read I/O op).

Note that this is a cut-down version of the fscache rewrite and does not
change any of the cookie and cache coherency handling.

Changes
=======
ver #4:
  - Rebase on top of folios.
  - Don't use wait_on_page_bit_killable().

ver #3:
  - v9fs_req_issue_op() needs to terminate the subrequest.
  - v9fs_write_end() needs to call SetPageUptodate() a bit more often.
  - It's not CONFIG_{AFS,V9FS}_FSCACHE[1]
  - v9fs_init_rreq() should take a ref on the p9_fid and the cleanup should
    drop it [from Dominique Martinet].

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-tested-by: Dominique Martinet <asmadeus@codewreck.org>
cc: v9fs-developer@lists.sourceforge.net
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/YUm+xucHxED+1MJp@codewreck.org/ [1]
Link: https://lore.kernel.org/r/163162772646.438332.16323773205855053535.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/163189109885.2509237.7153668924503399173.stgit@warthog.procyon.org.uk/ # rfc v2
Link: https://lore.kernel.org/r/163363943896.1980952.1226527304649419689.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/163551662876.1877519.14706391695553204156.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/163584179557.4023316.11089762304657644342.stgit@warthog.procyon.org.uk # rebase on folio
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
This commit is contained in:
David Howells
2021-11-02 08:29:55 +00:00
committed by Dominique Martinet
parent 0dc54bd4d6
commit eb497943fa
6 changed files with 128 additions and 340 deletions
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97
fs/9p/cache.h
View File

@ -7,9 +7,10 @@
#ifndef _9P_CACHE_H
#define _9P_CACHE_H
#ifdef CONFIG_9P_FSCACHE
#define FSCACHE_USE_NEW_IO_API
#include <linux/fscache.h>
#include <linux/spinlock.h>
#ifdef CONFIG_9P_FSCACHE
extern struct fscache_netfs v9fs_cache_netfs;
extern const struct fscache_cookie_def v9fs_cache_session_index_def;
@ -27,64 +28,6 @@ extern void v9fs_cache_inode_reset_cookie(struct inode *inode);
extern int __v9fs_cache_register(void);
extern void __v9fs_cache_unregister(void);
extern int __v9fs_fscache_release_page(struct page *page, gfp_t gfp);
extern void __v9fs_fscache_invalidate_page(struct page *page);
extern int __v9fs_readpage_from_fscache(struct inode *inode,
struct page *page);
extern int __v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages);
extern void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page);
extern void __v9fs_fscache_wait_on_page_write(struct inode *inode,
struct page *page);
static inline int v9fs_fscache_release_page(struct page *page,
gfp_t gfp)
{
return __v9fs_fscache_release_page(page, gfp);
}
static inline void v9fs_fscache_invalidate_page(struct page *page)
{
__v9fs_fscache_invalidate_page(page);
}
static inline int v9fs_readpage_from_fscache(struct inode *inode,
struct page *page)
{
return __v9fs_readpage_from_fscache(inode, page);
}
static inline int v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
return __v9fs_readpages_from_fscache(inode, mapping, pages,
nr_pages);
}
static inline void v9fs_readpage_to_fscache(struct inode *inode,
struct page *page)
{
if (PageFsCache(page))
__v9fs_readpage_to_fscache(inode, page);
}
static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
{
struct v9fs_inode *v9inode = V9FS_I(inode);
fscache_uncache_page(v9inode->fscache, page);
BUG_ON(PageFsCache(page));
}
static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
struct page *page)
{
return __v9fs_fscache_wait_on_page_write(inode, page);
}
#else /* CONFIG_9P_FSCACHE */
static inline void v9fs_cache_inode_get_cookie(struct inode *inode)
@ -99,39 +42,5 @@ static inline void v9fs_cache_inode_set_cookie(struct inode *inode, struct file
{
}
static inline int v9fs_fscache_release_page(struct page *page,
gfp_t gfp) {
return 1;
}
static inline void v9fs_fscache_invalidate_page(struct page *page) {}
static inline int v9fs_readpage_from_fscache(struct inode *inode,
struct page *page)
{
return -ENOBUFS;
}
static inline int v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
return -ENOBUFS;
}
static inline void v9fs_readpage_to_fscache(struct inode *inode,
struct page *page)
{}
static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
{}
static inline void v9fs_fscache_wait_on_page_write(struct inode *inode,
struct page *page)
{
return;
}
#endif /* CONFIG_9P_FSCACHE */
#endif /* _9P_CACHE_H */