673 lines
20 KiB
C
673 lines
20 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_PAGEMAP_H
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#define _LINUX_PAGEMAP_H
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/*
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* Copyright 1995 Linus Torvalds
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*/
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/list.h>
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#include <linux/highmem.h>
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#include <linux/compiler.h>
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#include <linux/uaccess.h>
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#include <linux/gfp.h>
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#include <linux/bitops.h>
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#include <linux/hardirq.h> /* for in_interrupt() */
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#include <linux/hugetlb_inline.h>
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struct pagevec;
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/*
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* Bits in mapping->flags.
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*/
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enum mapping_flags {
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AS_EIO = 0, /* IO error on async write */
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AS_ENOSPC = 1, /* ENOSPC on async write */
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AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
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AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
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AS_EXITING = 4, /* final truncate in progress */
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/* writeback related tags are not used */
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AS_NO_WRITEBACK_TAGS = 5,
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};
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/**
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* mapping_set_error - record a writeback error in the address_space
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* @mapping - the mapping in which an error should be set
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* @error - the error to set in the mapping
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*
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* When writeback fails in some way, we must record that error so that
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* userspace can be informed when fsync and the like are called. We endeavor
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* to report errors on any file that was open at the time of the error. Some
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* internal callers also need to know when writeback errors have occurred.
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*
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* When a writeback error occurs, most filesystems will want to call
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* mapping_set_error to record the error in the mapping so that it can be
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* reported when the application calls fsync(2).
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*/
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static inline void mapping_set_error(struct address_space *mapping, int error)
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{
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if (likely(!error))
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return;
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/* Record in wb_err for checkers using errseq_t based tracking */
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filemap_set_wb_err(mapping, error);
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/* Record it in flags for now, for legacy callers */
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if (error == -ENOSPC)
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set_bit(AS_ENOSPC, &mapping->flags);
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else
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set_bit(AS_EIO, &mapping->flags);
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}
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static inline void mapping_set_unevictable(struct address_space *mapping)
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{
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set_bit(AS_UNEVICTABLE, &mapping->flags);
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}
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static inline void mapping_clear_unevictable(struct address_space *mapping)
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{
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clear_bit(AS_UNEVICTABLE, &mapping->flags);
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}
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static inline int mapping_unevictable(struct address_space *mapping)
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{
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if (mapping)
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return test_bit(AS_UNEVICTABLE, &mapping->flags);
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return !!mapping;
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}
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static inline void mapping_set_exiting(struct address_space *mapping)
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{
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set_bit(AS_EXITING, &mapping->flags);
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}
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static inline int mapping_exiting(struct address_space *mapping)
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{
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return test_bit(AS_EXITING, &mapping->flags);
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}
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static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
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{
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set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
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}
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static inline int mapping_use_writeback_tags(struct address_space *mapping)
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{
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return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
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}
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static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
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{
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return mapping->gfp_mask;
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}
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/* Restricts the given gfp_mask to what the mapping allows. */
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static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
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gfp_t gfp_mask)
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{
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return mapping_gfp_mask(mapping) & gfp_mask;
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}
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/*
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* This is non-atomic. Only to be used before the mapping is activated.
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* Probably needs a barrier...
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*/
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static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
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{
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m->gfp_mask = mask;
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}
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void release_pages(struct page **pages, int nr);
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/*
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* speculatively take a reference to a page.
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* If the page is free (_refcount == 0), then _refcount is untouched, and 0
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* is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
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*
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* This function must be called inside the same rcu_read_lock() section as has
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* been used to lookup the page in the pagecache radix-tree (or page table):
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* this allows allocators to use a synchronize_rcu() to stabilize _refcount.
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*
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* Unless an RCU grace period has passed, the count of all pages coming out
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* of the allocator must be considered unstable. page_count may return higher
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* than expected, and put_page must be able to do the right thing when the
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* page has been finished with, no matter what it is subsequently allocated
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* for (because put_page is what is used here to drop an invalid speculative
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* reference).
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*
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* This is the interesting part of the lockless pagecache (and lockless
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* get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
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* has the following pattern:
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* 1. find page in radix tree
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* 2. conditionally increment refcount
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* 3. check the page is still in pagecache (if no, goto 1)
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*
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* Remove-side that cares about stability of _refcount (eg. reclaim) has the
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* following (with the i_pages lock held):
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* A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
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* B. remove page from pagecache
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* C. free the page
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*
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* There are 2 critical interleavings that matter:
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* - 2 runs before A: in this case, A sees elevated refcount and bails out
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* - A runs before 2: in this case, 2 sees zero refcount and retries;
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* subsequently, B will complete and 1 will find no page, causing the
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* lookup to return NULL.
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*
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* It is possible that between 1 and 2, the page is removed then the exact same
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* page is inserted into the same position in pagecache. That's OK: the
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* old find_get_page using a lock could equally have run before or after
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* such a re-insertion, depending on order that locks are granted.
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*
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* Lookups racing against pagecache insertion isn't a big problem: either 1
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* will find the page or it will not. Likewise, the old find_get_page could run
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* either before the insertion or afterwards, depending on timing.
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*/
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static inline int __page_cache_add_speculative(struct page *page, int count)
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{
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#ifdef CONFIG_TINY_RCU
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# ifdef CONFIG_PREEMPT_COUNT
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VM_BUG_ON(!in_atomic() && !irqs_disabled());
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# endif
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/*
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* Preempt must be disabled here - we rely on rcu_read_lock doing
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* this for us.
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*
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* Pagecache won't be truncated from interrupt context, so if we have
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* found a page in the radix tree here, we have pinned its refcount by
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* disabling preempt, and hence no need for the "speculative get" that
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* SMP requires.
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*/
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VM_BUG_ON_PAGE(page_count(page) == 0, page);
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page_ref_add(page, count);
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#else
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if (unlikely(!page_ref_add_unless(page, count, 0))) {
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/*
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* Either the page has been freed, or will be freed.
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* In either case, retry here and the caller should
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* do the right thing (see comments above).
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*/
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return 0;
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}
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#endif
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VM_BUG_ON_PAGE(PageTail(page), page);
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return 1;
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}
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static inline int page_cache_get_speculative(struct page *page)
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{
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return __page_cache_add_speculative(page, 1);
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}
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static inline int page_cache_add_speculative(struct page *page, int count)
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{
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return __page_cache_add_speculative(page, count);
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}
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#ifdef CONFIG_NUMA
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extern struct page *__page_cache_alloc(gfp_t gfp);
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#else
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static inline struct page *__page_cache_alloc(gfp_t gfp)
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{
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return alloc_pages(gfp, 0);
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}
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#endif
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static inline struct page *page_cache_alloc(struct address_space *x)
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{
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return __page_cache_alloc(mapping_gfp_mask(x));
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}
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static inline gfp_t readahead_gfp_mask(struct address_space *x)
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{
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return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
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}
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typedef int filler_t(void *, struct page *);
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pgoff_t page_cache_next_miss(struct address_space *mapping,
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pgoff_t index, unsigned long max_scan);
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pgoff_t page_cache_prev_miss(struct address_space *mapping,
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pgoff_t index, unsigned long max_scan);
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#define FGP_ACCESSED 0x00000001
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#define FGP_LOCK 0x00000002
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#define FGP_CREAT 0x00000004
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#define FGP_WRITE 0x00000008
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#define FGP_NOFS 0x00000010
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#define FGP_NOWAIT 0x00000020
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#define FGP_FOR_MMAP 0x00000040
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struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
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int fgp_flags, gfp_t cache_gfp_mask);
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/**
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* find_get_page - find and get a page reference
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* @mapping: the address_space to search
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* @offset: the page index
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*
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* Looks up the page cache slot at @mapping & @offset. If there is a
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* page cache page, it is returned with an increased refcount.
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*
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* Otherwise, %NULL is returned.
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*/
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static inline struct page *find_get_page(struct address_space *mapping,
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pgoff_t offset)
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{
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return pagecache_get_page(mapping, offset, 0, 0);
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}
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static inline struct page *find_get_page_flags(struct address_space *mapping,
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pgoff_t offset, int fgp_flags)
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{
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return pagecache_get_page(mapping, offset, fgp_flags, 0);
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}
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/**
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* find_lock_page - locate, pin and lock a pagecache page
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* @mapping: the address_space to search
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* @offset: the page index
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*
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* Looks up the page cache slot at @mapping & @offset. If there is a
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* page cache page, it is returned locked and with an increased
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* refcount.
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*
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* Otherwise, %NULL is returned.
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*
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* find_lock_page() may sleep.
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*/
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static inline struct page *find_lock_page(struct address_space *mapping,
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pgoff_t offset)
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{
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return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
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}
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/**
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* find_or_create_page - locate or add a pagecache page
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* @mapping: the page's address_space
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* @index: the page's index into the mapping
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* @gfp_mask: page allocation mode
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*
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* Looks up the page cache slot at @mapping & @offset. If there is a
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* page cache page, it is returned locked and with an increased
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* refcount.
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*
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* If the page is not present, a new page is allocated using @gfp_mask
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* and added to the page cache and the VM's LRU list. The page is
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* returned locked and with an increased refcount.
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*
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* On memory exhaustion, %NULL is returned.
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*
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* find_or_create_page() may sleep, even if @gfp_flags specifies an
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* atomic allocation!
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*/
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static inline struct page *find_or_create_page(struct address_space *mapping,
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pgoff_t offset, gfp_t gfp_mask)
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{
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return pagecache_get_page(mapping, offset,
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FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
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gfp_mask);
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}
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/**
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* grab_cache_page_nowait - returns locked page at given index in given cache
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* @mapping: target address_space
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* @index: the page index
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*
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* Same as grab_cache_page(), but do not wait if the page is unavailable.
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* This is intended for speculative data generators, where the data can
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* be regenerated if the page couldn't be grabbed. This routine should
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* be safe to call while holding the lock for another page.
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*
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* Clear __GFP_FS when allocating the page to avoid recursion into the fs
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* and deadlock against the caller's locked page.
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*/
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static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
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pgoff_t index)
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{
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return pagecache_get_page(mapping, index,
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FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
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mapping_gfp_mask(mapping));
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}
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/*
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* Given the page we found in the page cache, return the page corresponding
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* to this index in the file
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*/
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static inline struct page *find_subpage(struct page *head, pgoff_t index)
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{
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/* HugeTLBfs wants the head page regardless */
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if (PageHuge(head))
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return head;
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VM_BUG_ON_PAGE(PageTail(head), head);
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return head + (index & (compound_nr(head) - 1));
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}
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struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
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struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
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unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
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unsigned int nr_entries, struct page **entries,
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pgoff_t *indices);
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unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
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pgoff_t end, unsigned int nr_pages,
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struct page **pages);
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static inline unsigned find_get_pages(struct address_space *mapping,
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pgoff_t *start, unsigned int nr_pages,
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struct page **pages)
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{
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return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages,
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pages);
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}
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unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
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unsigned int nr_pages, struct page **pages);
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unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
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pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
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struct page **pages);
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static inline unsigned find_get_pages_tag(struct address_space *mapping,
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pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
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struct page **pages)
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{
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return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
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nr_pages, pages);
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}
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struct page *grab_cache_page_write_begin(struct address_space *mapping,
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pgoff_t index, unsigned flags);
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/*
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* Returns locked page at given index in given cache, creating it if needed.
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*/
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static inline struct page *grab_cache_page(struct address_space *mapping,
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pgoff_t index)
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{
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return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
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}
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extern struct page * read_cache_page(struct address_space *mapping,
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pgoff_t index, filler_t *filler, void *data);
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extern struct page * read_cache_page_gfp(struct address_space *mapping,
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pgoff_t index, gfp_t gfp_mask);
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extern int read_cache_pages(struct address_space *mapping,
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struct list_head *pages, filler_t *filler, void *data);
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static inline struct page *read_mapping_page(struct address_space *mapping,
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pgoff_t index, void *data)
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{
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return read_cache_page(mapping, index, NULL, data);
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}
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/*
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* Get index of the page with in radix-tree
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* (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
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*/
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static inline pgoff_t page_to_index(struct page *page)
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{
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pgoff_t pgoff;
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if (likely(!PageTransTail(page)))
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return page->index;
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/*
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* We don't initialize ->index for tail pages: calculate based on
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* head page
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*/
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pgoff = compound_head(page)->index;
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pgoff += page - compound_head(page);
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return pgoff;
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}
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/*
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* Get the offset in PAGE_SIZE.
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* (TODO: hugepage should have ->index in PAGE_SIZE)
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*/
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static inline pgoff_t page_to_pgoff(struct page *page)
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{
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if (unlikely(PageHeadHuge(page)))
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return page->index << compound_order(page);
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return page_to_index(page);
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}
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/*
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* Return byte-offset into filesystem object for page.
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*/
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static inline loff_t page_offset(struct page *page)
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{
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return ((loff_t)page->index) << PAGE_SHIFT;
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}
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static inline loff_t page_file_offset(struct page *page)
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{
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return ((loff_t)page_index(page)) << PAGE_SHIFT;
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}
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extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
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unsigned long address);
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static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
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unsigned long address)
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{
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pgoff_t pgoff;
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if (unlikely(is_vm_hugetlb_page(vma)))
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return linear_hugepage_index(vma, address);
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pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
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pgoff += vma->vm_pgoff;
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return pgoff;
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}
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extern void __lock_page(struct page *page);
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extern int __lock_page_killable(struct page *page);
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extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
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unsigned int flags);
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extern void unlock_page(struct page *page);
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/*
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* Return true if the page was successfully locked
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*/
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static inline int trylock_page(struct page *page)
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{
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page = compound_head(page);
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return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
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}
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/*
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* lock_page may only be called if we have the page's inode pinned.
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*/
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static inline void lock_page(struct page *page)
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{
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might_sleep();
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if (!trylock_page(page))
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__lock_page(page);
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}
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/*
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* lock_page_killable is like lock_page but can be interrupted by fatal
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* signals. It returns 0 if it locked the page and -EINTR if it was
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* killed while waiting.
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*/
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static inline int lock_page_killable(struct page *page)
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{
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might_sleep();
|
|
if (!trylock_page(page))
|
|
return __lock_page_killable(page);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* lock_page_or_retry - Lock the page, unless this would block and the
|
|
* caller indicated that it can handle a retry.
|
|
*
|
|
* Return value and mmap_sem implications depend on flags; see
|
|
* __lock_page_or_retry().
|
|
*/
|
|
static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
|
|
unsigned int flags)
|
|
{
|
|
might_sleep();
|
|
return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
|
|
}
|
|
|
|
/*
|
|
* This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
|
|
* and should not be used directly.
|
|
*/
|
|
extern void wait_on_page_bit(struct page *page, int bit_nr);
|
|
extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
|
|
|
|
/*
|
|
* Wait for a page to be unlocked.
|
|
*
|
|
* This must be called with the caller "holding" the page,
|
|
* ie with increased "page->count" so that the page won't
|
|
* go away during the wait..
|
|
*/
|
|
static inline void wait_on_page_locked(struct page *page)
|
|
{
|
|
if (PageLocked(page))
|
|
wait_on_page_bit(compound_head(page), PG_locked);
|
|
}
|
|
|
|
static inline int wait_on_page_locked_killable(struct page *page)
|
|
{
|
|
if (!PageLocked(page))
|
|
return 0;
|
|
return wait_on_page_bit_killable(compound_head(page), PG_locked);
|
|
}
|
|
|
|
extern void put_and_wait_on_page_locked(struct page *page);
|
|
|
|
void wait_on_page_writeback(struct page *page);
|
|
extern void end_page_writeback(struct page *page);
|
|
void wait_for_stable_page(struct page *page);
|
|
|
|
void page_endio(struct page *page, bool is_write, int err);
|
|
|
|
/*
|
|
* Add an arbitrary waiter to a page's wait queue
|
|
*/
|
|
extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
|
|
|
|
/*
|
|
* Fault everything in given userspace address range in.
|
|
*/
|
|
static inline int fault_in_pages_writeable(char __user *uaddr, int size)
|
|
{
|
|
char __user *end = uaddr + size - 1;
|
|
|
|
if (unlikely(size == 0))
|
|
return 0;
|
|
|
|
if (unlikely(uaddr > end))
|
|
return -EFAULT;
|
|
/*
|
|
* Writing zeroes into userspace here is OK, because we know that if
|
|
* the zero gets there, we'll be overwriting it.
|
|
*/
|
|
do {
|
|
if (unlikely(__put_user(0, uaddr) != 0))
|
|
return -EFAULT;
|
|
uaddr += PAGE_SIZE;
|
|
} while (uaddr <= end);
|
|
|
|
/* Check whether the range spilled into the next page. */
|
|
if (((unsigned long)uaddr & PAGE_MASK) ==
|
|
((unsigned long)end & PAGE_MASK))
|
|
return __put_user(0, end);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline int fault_in_pages_readable(const char __user *uaddr, int size)
|
|
{
|
|
volatile char c;
|
|
const char __user *end = uaddr + size - 1;
|
|
|
|
if (unlikely(size == 0))
|
|
return 0;
|
|
|
|
if (unlikely(uaddr > end))
|
|
return -EFAULT;
|
|
|
|
do {
|
|
if (unlikely(__get_user(c, uaddr) != 0))
|
|
return -EFAULT;
|
|
uaddr += PAGE_SIZE;
|
|
} while (uaddr <= end);
|
|
|
|
/* Check whether the range spilled into the next page. */
|
|
if (((unsigned long)uaddr & PAGE_MASK) ==
|
|
((unsigned long)end & PAGE_MASK)) {
|
|
return __get_user(c, end);
|
|
}
|
|
|
|
(void)c;
|
|
return 0;
|
|
}
|
|
|
|
int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
|
|
pgoff_t index, gfp_t gfp_mask);
|
|
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
|
|
pgoff_t index, gfp_t gfp_mask);
|
|
extern void delete_from_page_cache(struct page *page);
|
|
extern void __delete_from_page_cache(struct page *page, void *shadow);
|
|
int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
|
|
void delete_from_page_cache_batch(struct address_space *mapping,
|
|
struct pagevec *pvec);
|
|
|
|
/*
|
|
* Like add_to_page_cache_locked, but used to add newly allocated pages:
|
|
* the page is new, so we can just run __SetPageLocked() against it.
|
|
*/
|
|
static inline int add_to_page_cache(struct page *page,
|
|
struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
|
|
{
|
|
int error;
|
|
|
|
__SetPageLocked(page);
|
|
error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
|
|
if (unlikely(error))
|
|
__ClearPageLocked(page);
|
|
return error;
|
|
}
|
|
|
|
static inline unsigned long dir_pages(struct inode *inode)
|
|
{
|
|
return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
|
|
PAGE_SHIFT;
|
|
}
|
|
|
|
/**
|
|
* page_mkwrite_check_truncate - check if page was truncated
|
|
* @page: the page to check
|
|
* @inode: the inode to check the page against
|
|
*
|
|
* Returns the number of bytes in the page up to EOF,
|
|
* or -EFAULT if the page was truncated.
|
|
*/
|
|
static inline int page_mkwrite_check_truncate(struct page *page,
|
|
struct inode *inode)
|
|
{
|
|
loff_t size = i_size_read(inode);
|
|
pgoff_t index = size >> PAGE_SHIFT;
|
|
int offset = offset_in_page(size);
|
|
|
|
if (page->mapping != inode->i_mapping)
|
|
return -EFAULT;
|
|
|
|
/* page is wholly inside EOF */
|
|
if (page->index < index)
|
|
return PAGE_SIZE;
|
|
/* page is wholly past EOF */
|
|
if (page->index > index || !offset)
|
|
return -EFAULT;
|
|
/* page is partially inside EOF */
|
|
return offset;
|
|
}
|
|
|
|
#endif /* _LINUX_PAGEMAP_H */
|