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![Dan Magenheimer](/assets/img/avatar_default.png)
This third patch of eight in this cleancache series provides the core code for cleancache that interfaces between the hooks in VFS and individual filesystems and a cleancache backend. It also includes build and config patches. Two new files are added: mm/cleancache.c and include/linux/cleancache.h. Note that CONFIG_CLEANCACHE can default to on; in systems that do not provide a cleancache backend, all hooks devolve to a simple check of a global enable flag, so performance impact should be negligible but can be reduced to zero impact if config'ed off. However for this first commit, it defaults to off. Details and a FAQ can be found in Documentation/vm/cleancache.txt Credits: Cleancache_ops design derived from Jeremy Fitzhardinge design for tmem [v8: dan.magenheimer@oracle.com: fix exportfs call affecting btrfs] [v8: akpm@linux-foundation.org: use static inline function, not macro] [v7: dan.magenheimer@oracle.com: cleanup sysfs and remove cleancache prefix] [v6: JBeulich@novell.com: robustly handle buggy fs encode_fh actor definition] [v5: jeremy@goop.org: clean up global usage and static var names] [v5: jeremy@goop.org: simplify init hook and any future fs init changes] [v5: hch@infradead.org: cleaner non-global interface for ops registration] [v4: adilger@sun.com: interface must support exportfs FS's] [v4: hch@infradead.org: interface must support 64-bit FS on 32-bit kernel] [v3: akpm@linux-foundation.org: use one ops struct to avoid pointer hops] [v3: akpm@linux-foundation.org: document and ensure PageLocked reqts are met] [v3: ngupta@vflare.org: fix success/fail codes, change funcs to void] [v2: viro@ZenIV.linux.org.uk: use sane types] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Jeremy Fitzhardinge <jeremy@goop.org> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Acked-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Nitin Gupta <ngupta@vflare.org> Acked-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: Andreas Dilger <adilger@sun.com> Acked-by: Jan Beulich <JBeulich@novell.com> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik Van Riel <riel@redhat.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Ted Ts'o <tytso@mit.edu> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <joel.becker@oracle.com>
122 lines
3.7 KiB
C
122 lines
3.7 KiB
C
#ifndef _LINUX_CLEANCACHE_H
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#define _LINUX_CLEANCACHE_H
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#include <linux/fs.h>
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#include <linux/exportfs.h>
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#include <linux/mm.h>
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#define CLEANCACHE_KEY_MAX 6
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/*
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* cleancache requires every file with a page in cleancache to have a
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* unique key unless/until the file is removed/truncated. For some
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* filesystems, the inode number is unique, but for "modern" filesystems
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* an exportable filehandle is required (see exportfs.h)
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*/
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struct cleancache_filekey {
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union {
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ino_t ino;
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__u32 fh[CLEANCACHE_KEY_MAX];
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u32 key[CLEANCACHE_KEY_MAX];
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} u;
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};
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struct cleancache_ops {
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int (*init_fs)(size_t);
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int (*init_shared_fs)(char *uuid, size_t);
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int (*get_page)(int, struct cleancache_filekey,
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pgoff_t, struct page *);
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void (*put_page)(int, struct cleancache_filekey,
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pgoff_t, struct page *);
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void (*flush_page)(int, struct cleancache_filekey, pgoff_t);
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void (*flush_inode)(int, struct cleancache_filekey);
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void (*flush_fs)(int);
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};
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extern struct cleancache_ops
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cleancache_register_ops(struct cleancache_ops *ops);
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extern void __cleancache_init_fs(struct super_block *);
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extern void __cleancache_init_shared_fs(char *, struct super_block *);
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extern int __cleancache_get_page(struct page *);
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extern void __cleancache_put_page(struct page *);
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extern void __cleancache_flush_page(struct address_space *, struct page *);
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extern void __cleancache_flush_inode(struct address_space *);
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extern void __cleancache_flush_fs(struct super_block *);
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extern int cleancache_enabled;
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#ifdef CONFIG_CLEANCACHE
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static inline bool cleancache_fs_enabled(struct page *page)
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{
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return page->mapping->host->i_sb->cleancache_poolid >= 0;
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}
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static inline bool cleancache_fs_enabled_mapping(struct address_space *mapping)
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{
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return mapping->host->i_sb->cleancache_poolid >= 0;
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}
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#else
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#define cleancache_enabled (0)
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#define cleancache_fs_enabled(_page) (0)
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#define cleancache_fs_enabled_mapping(_page) (0)
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#endif
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/*
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* The shim layer provided by these inline functions allows the compiler
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* to reduce all cleancache hooks to nothingness if CONFIG_CLEANCACHE
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* is disabled, to a single global variable check if CONFIG_CLEANCACHE
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* is enabled but no cleancache "backend" has dynamically enabled it,
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* and, for the most frequent cleancache ops, to a single global variable
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* check plus a superblock element comparison if CONFIG_CLEANCACHE is enabled
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* and a cleancache backend has dynamically enabled cleancache, but the
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* filesystem referenced by that cleancache op has not enabled cleancache.
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* As a result, CONFIG_CLEANCACHE can be enabled by default with essentially
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* no measurable performance impact.
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*/
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static inline void cleancache_init_fs(struct super_block *sb)
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{
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if (cleancache_enabled)
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__cleancache_init_fs(sb);
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}
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static inline void cleancache_init_shared_fs(char *uuid, struct super_block *sb)
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{
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if (cleancache_enabled)
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__cleancache_init_shared_fs(uuid, sb);
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}
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static inline int cleancache_get_page(struct page *page)
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{
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int ret = -1;
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if (cleancache_enabled && cleancache_fs_enabled(page))
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ret = __cleancache_get_page(page);
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return ret;
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}
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static inline void cleancache_put_page(struct page *page)
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{
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if (cleancache_enabled && cleancache_fs_enabled(page))
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__cleancache_put_page(page);
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}
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static inline void cleancache_flush_page(struct address_space *mapping,
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struct page *page)
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{
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/* careful... page->mapping is NULL sometimes when this is called */
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if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
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__cleancache_flush_page(mapping, page);
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}
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static inline void cleancache_flush_inode(struct address_space *mapping)
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{
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if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
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__cleancache_flush_inode(mapping);
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}
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static inline void cleancache_flush_fs(struct super_block *sb)
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{
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if (cleancache_enabled)
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__cleancache_flush_fs(sb);
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}
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#endif /* _LINUX_CLEANCACHE_H */
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