LCOV - code coverage report
Current view: top level - include/linux - pagemap.h (source / functions) Hit Total Coverage
Test: Real Lines: 52 63 82.5 %
Date: 2020-10-17 15:46:16 Functions: 0 9 0.0 %
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0 */
       2                 :            : #ifndef _LINUX_PAGEMAP_H
       3                 :            : #define _LINUX_PAGEMAP_H
       4                 :            : 
       5                 :            : /*
       6                 :            :  * Copyright 1995 Linus Torvalds
       7                 :            :  */
       8                 :            : #include <linux/mm.h>
       9                 :            : #include <linux/fs.h>
      10                 :            : #include <linux/list.h>
      11                 :            : #include <linux/highmem.h>
      12                 :            : #include <linux/compiler.h>
      13                 :            : #include <linux/uaccess.h>
      14                 :            : #include <linux/gfp.h>
      15                 :            : #include <linux/bitops.h>
      16                 :            : #include <linux/hardirq.h> /* for in_interrupt() */
      17                 :            : #include <linux/hugetlb_inline.h>
      18                 :            : 
      19                 :            : struct pagevec;
      20                 :            : 
      21                 :            : /*
      22                 :            :  * Bits in mapping->flags.
      23                 :            :  */
      24                 :            : enum mapping_flags {
      25                 :            :         AS_EIO          = 0,    /* IO error on async write */
      26                 :            :         AS_ENOSPC       = 1,    /* ENOSPC on async write */
      27                 :            :         AS_MM_ALL_LOCKS = 2,    /* under mm_take_all_locks() */
      28                 :            :         AS_UNEVICTABLE  = 3,    /* e.g., ramdisk, SHM_LOCK */
      29                 :            :         AS_EXITING      = 4,    /* final truncate in progress */
      30                 :            :         /* writeback related tags are not used */
      31                 :            :         AS_NO_WRITEBACK_TAGS = 5,
      32                 :            : };
      33                 :            : 
      34                 :            : /**
      35                 :            :  * mapping_set_error - record a writeback error in the address_space
      36                 :            :  * @mapping - the mapping in which an error should be set
      37                 :            :  * @error - the error to set in the mapping
      38                 :            :  *
      39                 :            :  * When writeback fails in some way, we must record that error so that
      40                 :            :  * userspace can be informed when fsync and the like are called.  We endeavor
      41                 :            :  * to report errors on any file that was open at the time of the error.  Some
      42                 :            :  * internal callers also need to know when writeback errors have occurred.
      43                 :            :  *
      44                 :            :  * When a writeback error occurs, most filesystems will want to call
      45                 :            :  * mapping_set_error to record the error in the mapping so that it can be
      46                 :            :  * reported when the application calls fsync(2).
      47                 :            :  */
      48                 :          3 : static inline void mapping_set_error(struct address_space *mapping, int error)
      49                 :            : {
      50                 :          3 :         if (likely(!error))
      51                 :          3 :                 return;
      52                 :            : 
      53                 :            :         /* Record in wb_err for checkers using errseq_t based tracking */
      54                 :            :         filemap_set_wb_err(mapping, error);
      55                 :            : 
      56                 :            :         /* Record it in flags for now, for legacy callers */
      57                 :          0 :         if (error == -ENOSPC)
      58                 :          0 :                 set_bit(AS_ENOSPC, &mapping->flags);
      59                 :            :         else
      60                 :          0 :                 set_bit(AS_EIO, &mapping->flags);
      61                 :            : }
      62                 :            : 
      63                 :            : static inline void mapping_set_unevictable(struct address_space *mapping)
      64                 :            : {
      65                 :          3 :         set_bit(AS_UNEVICTABLE, &mapping->flags);
      66                 :            : }
      67                 :            : 
      68                 :            : static inline void mapping_clear_unevictable(struct address_space *mapping)
      69                 :            : {
      70                 :          0 :         clear_bit(AS_UNEVICTABLE, &mapping->flags);
      71                 :            : }
      72                 :            : 
      73                 :            : static inline int mapping_unevictable(struct address_space *mapping)
      74                 :            : {
      75                 :          3 :         if (mapping)
      76                 :            :                 return test_bit(AS_UNEVICTABLE, &mapping->flags);
      77                 :          3 :         return !!mapping;
      78                 :            : }
      79                 :            : 
      80                 :            : static inline void mapping_set_exiting(struct address_space *mapping)
      81                 :            : {
      82                 :          3 :         set_bit(AS_EXITING, &mapping->flags);
      83                 :            : }
      84                 :            : 
      85                 :            : static inline int mapping_exiting(struct address_space *mapping)
      86                 :            : {
      87                 :            :         return test_bit(AS_EXITING, &mapping->flags);
      88                 :            : }
      89                 :            : 
      90                 :            : static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
      91                 :            : {
      92                 :          3 :         set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
      93                 :            : }
      94                 :            : 
      95                 :            : static inline int mapping_use_writeback_tags(struct address_space *mapping)
      96                 :            : {
      97                 :            :         return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
      98                 :            : }
      99                 :            : 
     100                 :            : static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
     101                 :            : {
     102                 :          3 :         return mapping->gfp_mask;
     103                 :            : }
     104                 :            : 
     105                 :            : /* Restricts the given gfp_mask to what the mapping allows. */
     106                 :            : static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
     107                 :            :                 gfp_t gfp_mask)
     108                 :            : {
     109                 :          3 :         return mapping_gfp_mask(mapping) & gfp_mask;
     110                 :            : }
     111                 :            : 
     112                 :            : /*
     113                 :            :  * This is non-atomic.  Only to be used before the mapping is activated.
     114                 :            :  * Probably needs a barrier...
     115                 :            :  */
     116                 :            : static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
     117                 :            : {
     118                 :          3 :         m->gfp_mask = mask;
     119                 :            : }
     120                 :            : 
     121                 :            : void release_pages(struct page **pages, int nr);
     122                 :            : 
     123                 :            : /*
     124                 :            :  * speculatively take a reference to a page.
     125                 :            :  * If the page is free (_refcount == 0), then _refcount is untouched, and 0
     126                 :            :  * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
     127                 :            :  *
     128                 :            :  * This function must be called inside the same rcu_read_lock() section as has
     129                 :            :  * been used to lookup the page in the pagecache radix-tree (or page table):
     130                 :            :  * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
     131                 :            :  *
     132                 :            :  * Unless an RCU grace period has passed, the count of all pages coming out
     133                 :            :  * of the allocator must be considered unstable. page_count may return higher
     134                 :            :  * than expected, and put_page must be able to do the right thing when the
     135                 :            :  * page has been finished with, no matter what it is subsequently allocated
     136                 :            :  * for (because put_page is what is used here to drop an invalid speculative
     137                 :            :  * reference).
     138                 :            :  *
     139                 :            :  * This is the interesting part of the lockless pagecache (and lockless
     140                 :            :  * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
     141                 :            :  * has the following pattern:
     142                 :            :  * 1. find page in radix tree
     143                 :            :  * 2. conditionally increment refcount
     144                 :            :  * 3. check the page is still in pagecache (if no, goto 1)
     145                 :            :  *
     146                 :            :  * Remove-side that cares about stability of _refcount (eg. reclaim) has the
     147                 :            :  * following (with the i_pages lock held):
     148                 :            :  * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
     149                 :            :  * B. remove page from pagecache
     150                 :            :  * C. free the page
     151                 :            :  *
     152                 :            :  * There are 2 critical interleavings that matter:
     153                 :            :  * - 2 runs before A: in this case, A sees elevated refcount and bails out
     154                 :            :  * - A runs before 2: in this case, 2 sees zero refcount and retries;
     155                 :            :  *   subsequently, B will complete and 1 will find no page, causing the
     156                 :            :  *   lookup to return NULL.
     157                 :            :  *
     158                 :            :  * It is possible that between 1 and 2, the page is removed then the exact same
     159                 :            :  * page is inserted into the same position in pagecache. That's OK: the
     160                 :            :  * old find_get_page using a lock could equally have run before or after
     161                 :            :  * such a re-insertion, depending on order that locks are granted.
     162                 :            :  *
     163                 :            :  * Lookups racing against pagecache insertion isn't a big problem: either 1
     164                 :            :  * will find the page or it will not. Likewise, the old find_get_page could run
     165                 :            :  * either before the insertion or afterwards, depending on timing.
     166                 :            :  */
     167                 :            : static inline int __page_cache_add_speculative(struct page *page, int count)
     168                 :            : {
     169                 :            : #ifdef CONFIG_TINY_RCU
     170                 :            : # ifdef CONFIG_PREEMPT_COUNT
     171                 :            :         VM_BUG_ON(!in_atomic() && !irqs_disabled());
     172                 :            : # endif
     173                 :            :         /*
     174                 :            :          * Preempt must be disabled here - we rely on rcu_read_lock doing
     175                 :            :          * this for us.
     176                 :            :          *
     177                 :            :          * Pagecache won't be truncated from interrupt context, so if we have
     178                 :            :          * found a page in the radix tree here, we have pinned its refcount by
     179                 :            :          * disabling preempt, and hence no need for the "speculative get" that
     180                 :            :          * SMP requires.
     181                 :            :          */
     182                 :            :         VM_BUG_ON_PAGE(page_count(page) == 0, page);
     183                 :            :         page_ref_add(page, count);
     184                 :            : 
     185                 :            : #else
     186                 :          3 :         if (unlikely(!page_ref_add_unless(page, count, 0))) {
     187                 :            :                 /*
     188                 :            :                  * Either the page has been freed, or will be freed.
     189                 :            :                  * In either case, retry here and the caller should
     190                 :            :                  * do the right thing (see comments above).
     191                 :            :                  */
     192                 :            :                 return 0;
     193                 :            :         }
     194                 :            : #endif
     195                 :            :         VM_BUG_ON_PAGE(PageTail(page), page);
     196                 :            : 
     197                 :            :         return 1;
     198                 :            : }
     199                 :            : 
     200                 :            : static inline int page_cache_get_speculative(struct page *page)
     201                 :            : {
     202                 :            :         return __page_cache_add_speculative(page, 1);
     203                 :            : }
     204                 :            : 
     205                 :            : static inline int page_cache_add_speculative(struct page *page, int count)
     206                 :            : {
     207                 :            :         return __page_cache_add_speculative(page, count);
     208                 :            : }
     209                 :            : 
     210                 :            : #ifdef CONFIG_NUMA
     211                 :            : extern struct page *__page_cache_alloc(gfp_t gfp);
     212                 :            : #else
     213                 :            : static inline struct page *__page_cache_alloc(gfp_t gfp)
     214                 :            : {
     215                 :            :         return alloc_pages(gfp, 0);
     216                 :            : }
     217                 :            : #endif
     218                 :            : 
     219                 :            : static inline struct page *page_cache_alloc(struct address_space *x)
     220                 :            : {
     221                 :            :         return __page_cache_alloc(mapping_gfp_mask(x));
     222                 :            : }
     223                 :            : 
     224                 :            : static inline gfp_t readahead_gfp_mask(struct address_space *x)
     225                 :            : {
     226                 :          3 :         return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
     227                 :            : }
     228                 :            : 
     229                 :            : typedef int filler_t(void *, struct page *);
     230                 :            : 
     231                 :            : pgoff_t page_cache_next_miss(struct address_space *mapping,
     232                 :            :                              pgoff_t index, unsigned long max_scan);
     233                 :            : pgoff_t page_cache_prev_miss(struct address_space *mapping,
     234                 :            :                              pgoff_t index, unsigned long max_scan);
     235                 :            : 
     236                 :            : #define FGP_ACCESSED            0x00000001
     237                 :            : #define FGP_LOCK                0x00000002
     238                 :            : #define FGP_CREAT               0x00000004
     239                 :            : #define FGP_WRITE               0x00000008
     240                 :            : #define FGP_NOFS                0x00000010
     241                 :            : #define FGP_NOWAIT              0x00000020
     242                 :            : #define FGP_FOR_MMAP            0x00000040
     243                 :            : 
     244                 :            : struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
     245                 :            :                 int fgp_flags, gfp_t cache_gfp_mask);
     246                 :            : 
     247                 :            : /**
     248                 :            :  * find_get_page - find and get a page reference
     249                 :            :  * @mapping: the address_space to search
     250                 :            :  * @offset: the page index
     251                 :            :  *
     252                 :            :  * Looks up the page cache slot at @mapping & @offset.  If there is a
     253                 :            :  * page cache page, it is returned with an increased refcount.
     254                 :            :  *
     255                 :            :  * Otherwise, %NULL is returned.
     256                 :            :  */
     257                 :            : static inline struct page *find_get_page(struct address_space *mapping,
     258                 :            :                                         pgoff_t offset)
     259                 :            : {
     260                 :          3 :         return pagecache_get_page(mapping, offset, 0, 0);
     261                 :            : }
     262                 :            : 
     263                 :            : static inline struct page *find_get_page_flags(struct address_space *mapping,
     264                 :            :                                         pgoff_t offset, int fgp_flags)
     265                 :            : {
     266                 :          3 :         return pagecache_get_page(mapping, offset, fgp_flags, 0);
     267                 :            : }
     268                 :            : 
     269                 :            : /**
     270                 :            :  * find_lock_page - locate, pin and lock a pagecache page
     271                 :            :  * @mapping: the address_space to search
     272                 :            :  * @offset: the page index
     273                 :            :  *
     274                 :            :  * Looks up the page cache slot at @mapping & @offset.  If there is a
     275                 :            :  * page cache page, it is returned locked and with an increased
     276                 :            :  * refcount.
     277                 :            :  *
     278                 :            :  * Otherwise, %NULL is returned.
     279                 :            :  *
     280                 :            :  * find_lock_page() may sleep.
     281                 :            :  */
     282                 :            : static inline struct page *find_lock_page(struct address_space *mapping,
     283                 :            :                                         pgoff_t offset)
     284                 :            : {
     285                 :          0 :         return pagecache_get_page(mapping, offset, FGP_LOCK, 0);
     286                 :            : }
     287                 :            : 
     288                 :            : /**
     289                 :            :  * find_or_create_page - locate or add a pagecache page
     290                 :            :  * @mapping: the page's address_space
     291                 :            :  * @index: the page's index into the mapping
     292                 :            :  * @gfp_mask: page allocation mode
     293                 :            :  *
     294                 :            :  * Looks up the page cache slot at @mapping & @offset.  If there is a
     295                 :            :  * page cache page, it is returned locked and with an increased
     296                 :            :  * refcount.
     297                 :            :  *
     298                 :            :  * If the page is not present, a new page is allocated using @gfp_mask
     299                 :            :  * and added to the page cache and the VM's LRU list.  The page is
     300                 :            :  * returned locked and with an increased refcount.
     301                 :            :  *
     302                 :            :  * On memory exhaustion, %NULL is returned.
     303                 :            :  *
     304                 :            :  * find_or_create_page() may sleep, even if @gfp_flags specifies an
     305                 :            :  * atomic allocation!
     306                 :            :  */
     307                 :            : static inline struct page *find_or_create_page(struct address_space *mapping,
     308                 :            :                                         pgoff_t offset, gfp_t gfp_mask)
     309                 :            : {
     310                 :          3 :         return pagecache_get_page(mapping, offset,
     311                 :            :                                         FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
     312                 :            :                                         gfp_mask);
     313                 :            : }
     314                 :            : 
     315                 :            : /**
     316                 :            :  * grab_cache_page_nowait - returns locked page at given index in given cache
     317                 :            :  * @mapping: target address_space
     318                 :            :  * @index: the page index
     319                 :            :  *
     320                 :            :  * Same as grab_cache_page(), but do not wait if the page is unavailable.
     321                 :            :  * This is intended for speculative data generators, where the data can
     322                 :            :  * be regenerated if the page couldn't be grabbed.  This routine should
     323                 :            :  * be safe to call while holding the lock for another page.
     324                 :            :  *
     325                 :            :  * Clear __GFP_FS when allocating the page to avoid recursion into the fs
     326                 :            :  * and deadlock against the caller's locked page.
     327                 :            :  */
     328                 :            : static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
     329                 :            :                                 pgoff_t index)
     330                 :            : {
     331                 :            :         return pagecache_get_page(mapping, index,
     332                 :            :                         FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
     333                 :            :                         mapping_gfp_mask(mapping));
     334                 :            : }
     335                 :            : 
     336                 :          3 : static inline struct page *find_subpage(struct page *page, pgoff_t offset)
     337                 :            : {
     338                 :            :         if (PageHuge(page))
     339                 :            :                 return page;
     340                 :            : 
     341                 :            :         VM_BUG_ON_PAGE(PageTail(page), page);
     342                 :            : 
     343                 :          3 :         return page + (offset & (compound_nr(page) - 1));
     344                 :            : }
     345                 :            : 
     346                 :            : struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
     347                 :            : struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
     348                 :            : unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
     349                 :            :                           unsigned int nr_entries, struct page **entries,
     350                 :            :                           pgoff_t *indices);
     351                 :            : unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
     352                 :            :                         pgoff_t end, unsigned int nr_pages,
     353                 :            :                         struct page **pages);
     354                 :            : static inline unsigned find_get_pages(struct address_space *mapping,
     355                 :            :                         pgoff_t *start, unsigned int nr_pages,
     356                 :            :                         struct page **pages)
     357                 :            : {
     358                 :            :         return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages,
     359                 :            :                                     pages);
     360                 :            : }
     361                 :            : unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
     362                 :            :                                unsigned int nr_pages, struct page **pages);
     363                 :            : unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
     364                 :            :                         pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
     365                 :            :                         struct page **pages);
     366                 :            : static inline unsigned find_get_pages_tag(struct address_space *mapping,
     367                 :            :                         pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
     368                 :            :                         struct page **pages)
     369                 :            : {
     370                 :          0 :         return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
     371                 :            :                                         nr_pages, pages);
     372                 :            : }
     373                 :            : 
     374                 :            : struct page *grab_cache_page_write_begin(struct address_space *mapping,
     375                 :            :                         pgoff_t index, unsigned flags);
     376                 :            : 
     377                 :            : /*
     378                 :            :  * Returns locked page at given index in given cache, creating it if needed.
     379                 :            :  */
     380                 :            : static inline struct page *grab_cache_page(struct address_space *mapping,
     381                 :            :                                                                 pgoff_t index)
     382                 :            : {
     383                 :            :         return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
     384                 :            : }
     385                 :            : 
     386                 :            : extern struct page * read_cache_page(struct address_space *mapping,
     387                 :            :                                 pgoff_t index, filler_t *filler, void *data);
     388                 :            : extern struct page * read_cache_page_gfp(struct address_space *mapping,
     389                 :            :                                 pgoff_t index, gfp_t gfp_mask);
     390                 :            : extern int read_cache_pages(struct address_space *mapping,
     391                 :            :                 struct list_head *pages, filler_t *filler, void *data);
     392                 :            : 
     393                 :            : static inline struct page *read_mapping_page(struct address_space *mapping,
     394                 :            :                                 pgoff_t index, void *data)
     395                 :            : {
     396                 :          3 :         return read_cache_page(mapping, index, NULL, data);
     397                 :            : }
     398                 :            : 
     399                 :            : /*
     400                 :            :  * Get index of the page with in radix-tree
     401                 :            :  * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
     402                 :            :  */
     403                 :            : static inline pgoff_t page_to_index(struct page *page)
     404                 :            : {
     405                 :            :         pgoff_t pgoff;
     406                 :            : 
     407                 :            :         if (likely(!PageTransTail(page)))
     408                 :          3 :                 return page->index;
     409                 :            : 
     410                 :            :         /*
     411                 :            :          *  We don't initialize ->index for tail pages: calculate based on
     412                 :            :          *  head page
     413                 :            :          */
     414                 :            :         pgoff = compound_head(page)->index;
     415                 :            :         pgoff += page - compound_head(page);
     416                 :            :         return pgoff;
     417                 :            : }
     418                 :            : 
     419                 :            : /*
     420                 :            :  * Get the offset in PAGE_SIZE.
     421                 :            :  * (TODO: hugepage should have ->index in PAGE_SIZE)
     422                 :            :  */
     423                 :            : static inline pgoff_t page_to_pgoff(struct page *page)
     424                 :            : {
     425                 :            :         if (unlikely(PageHeadHuge(page)))
     426                 :            :                 return page->index << compound_order(page);
     427                 :            : 
     428                 :            :         return page_to_index(page);
     429                 :            : }
     430                 :            : 
     431                 :            : /*
     432                 :            :  * Return byte-offset into filesystem object for page.
     433                 :            :  */
     434                 :            : static inline loff_t page_offset(struct page *page)
     435                 :            : {
     436                 :          3 :         return ((loff_t)page->index) << PAGE_SHIFT;
     437                 :            : }
     438                 :            : 
     439                 :            : static inline loff_t page_file_offset(struct page *page)
     440                 :            : {
     441                 :          0 :         return ((loff_t)page_index(page)) << PAGE_SHIFT;
     442                 :            : }
     443                 :            : 
     444                 :            : extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
     445                 :            :                                      unsigned long address);
     446                 :            : 
     447                 :            : static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
     448                 :            :                                         unsigned long address)
     449                 :            : {
     450                 :            :         pgoff_t pgoff;
     451                 :            :         if (unlikely(is_vm_hugetlb_page(vma)))
     452                 :            :                 return linear_hugepage_index(vma, address);
     453                 :          3 :         pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
     454                 :          3 :         pgoff += vma->vm_pgoff;
     455                 :            :         return pgoff;
     456                 :            : }
     457                 :            : 
     458                 :            : extern void __lock_page(struct page *page);
     459                 :            : extern int __lock_page_killable(struct page *page);
     460                 :            : extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
     461                 :            :                                 unsigned int flags);
     462                 :            : extern void unlock_page(struct page *page);
     463                 :            : 
     464                 :            : /*
     465                 :            :  * Return true if the page was successfully locked
     466                 :            :  */
     467                 :          3 : static inline int trylock_page(struct page *page)
     468                 :            : {
     469                 :            :         page = compound_head(page);
     470                 :          3 :         return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
     471                 :            : }
     472                 :            : 
     473                 :            : /*
     474                 :            :  * lock_page may only be called if we have the page's inode pinned.
     475                 :            :  */
     476                 :          3 : static inline void lock_page(struct page *page)
     477                 :            : {
     478                 :          3 :         might_sleep();
     479                 :          3 :         if (!trylock_page(page))
     480                 :          3 :                 __lock_page(page);
     481                 :          3 : }
     482                 :            : 
     483                 :            : /*
     484                 :            :  * lock_page_killable is like lock_page but can be interrupted by fatal
     485                 :            :  * signals.  It returns 0 if it locked the page and -EINTR if it was
     486                 :            :  * killed while waiting.
     487                 :            :  */
     488                 :          3 : static inline int lock_page_killable(struct page *page)
     489                 :            : {
     490                 :          3 :         might_sleep();
     491                 :          3 :         if (!trylock_page(page))
     492                 :          2 :                 return __lock_page_killable(page);
     493                 :            :         return 0;
     494                 :            : }
     495                 :            : 
     496                 :            : /*
     497                 :            :  * lock_page_or_retry - Lock the page, unless this would block and the
     498                 :            :  * caller indicated that it can handle a retry.
     499                 :            :  *
     500                 :            :  * Return value and mmap_sem implications depend on flags; see
     501                 :            :  * __lock_page_or_retry().
     502                 :            :  */
     503                 :          0 : static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
     504                 :            :                                      unsigned int flags)
     505                 :            : {
     506                 :          0 :         might_sleep();
     507                 :          0 :         return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
     508                 :            : }
     509                 :            : 
     510                 :            : /*
     511                 :            :  * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
     512                 :            :  * and should not be used directly.
     513                 :            :  */
     514                 :            : extern void wait_on_page_bit(struct page *page, int bit_nr);
     515                 :            : extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
     516                 :            : 
     517                 :            : /* 
     518                 :            :  * Wait for a page to be unlocked.
     519                 :            :  *
     520                 :            :  * This must be called with the caller "holding" the page,
     521                 :            :  * ie with increased "page->count" so that the page won't
     522                 :            :  * go away during the wait..
     523                 :            :  */
     524                 :          3 : static inline void wait_on_page_locked(struct page *page)
     525                 :            : {
     526                 :          3 :         if (PageLocked(page))
     527                 :          0 :                 wait_on_page_bit(compound_head(page), PG_locked);
     528                 :          3 : }
     529                 :            : 
     530                 :          3 : static inline int wait_on_page_locked_killable(struct page *page)
     531                 :            : {
     532                 :          3 :         if (!PageLocked(page))
     533                 :            :                 return 0;
     534                 :          3 :         return wait_on_page_bit_killable(compound_head(page), PG_locked);
     535                 :            : }
     536                 :            : 
     537                 :            : extern void put_and_wait_on_page_locked(struct page *page);
     538                 :            : 
     539                 :            : void wait_on_page_writeback(struct page *page);
     540                 :            : extern void end_page_writeback(struct page *page);
     541                 :            : void wait_for_stable_page(struct page *page);
     542                 :            : 
     543                 :            : void page_endio(struct page *page, bool is_write, int err);
     544                 :            : 
     545                 :            : /*
     546                 :            :  * Add an arbitrary waiter to a page's wait queue
     547                 :            :  */
     548                 :            : extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
     549                 :            : 
     550                 :            : /*
     551                 :            :  * Fault everything in given userspace address range in.
     552                 :            :  */
     553                 :            : static inline int fault_in_pages_writeable(char __user *uaddr, int size)
     554                 :            : {
     555                 :            :         char __user *end = uaddr + size - 1;
     556                 :            : 
     557                 :            :         if (unlikely(size == 0))
     558                 :            :                 return 0;
     559                 :            : 
     560                 :            :         if (unlikely(uaddr > end))
     561                 :            :                 return -EFAULT;
     562                 :            :         /*
     563                 :            :          * Writing zeroes into userspace here is OK, because we know that if
     564                 :            :          * the zero gets there, we'll be overwriting it.
     565                 :            :          */
     566                 :            :         do {
     567                 :            :                 if (unlikely(__put_user(0, uaddr) != 0))
     568                 :            :                         return -EFAULT;
     569                 :            :                 uaddr += PAGE_SIZE;
     570                 :            :         } while (uaddr <= end);
     571                 :            : 
     572                 :            :         /* Check whether the range spilled into the next page. */
     573                 :            :         if (((unsigned long)uaddr & PAGE_MASK) ==
     574                 :            :                         ((unsigned long)end & PAGE_MASK))
     575                 :            :                 return __put_user(0, end);
     576                 :            : 
     577                 :            :         return 0;
     578                 :            : }
     579                 :            : 
     580                 :          3 : static inline int fault_in_pages_readable(const char __user *uaddr, int size)
     581                 :            : {
     582                 :            :         volatile char c;
     583                 :          3 :         const char __user *end = uaddr + size - 1;
     584                 :            : 
     585                 :          3 :         if (unlikely(size == 0))
     586                 :            :                 return 0;
     587                 :            : 
     588                 :          3 :         if (unlikely(uaddr > end))
     589                 :            :                 return -EFAULT;
     590                 :            : 
     591                 :            :         do {
     592                 :          3 :                 if (unlikely(__get_user(c, uaddr) != 0))
     593                 :            :                         return -EFAULT;
     594                 :          3 :                 uaddr += PAGE_SIZE;
     595                 :          3 :         } while (uaddr <= end);
     596                 :            : 
     597                 :            :         /* Check whether the range spilled into the next page. */
     598                 :          3 :         if (((unsigned long)uaddr & PAGE_MASK) ==
     599                 :          3 :                         ((unsigned long)end & PAGE_MASK)) {
     600                 :          3 :                 return __get_user(c, end);
     601                 :            :         }
     602                 :            : 
     603                 :          3 :         (void)c;
     604                 :          3 :         return 0;
     605                 :            : }
     606                 :            : 
     607                 :            : int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
     608                 :            :                                 pgoff_t index, gfp_t gfp_mask);
     609                 :            : int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
     610                 :            :                                 pgoff_t index, gfp_t gfp_mask);
     611                 :            : extern void delete_from_page_cache(struct page *page);
     612                 :            : extern void __delete_from_page_cache(struct page *page, void *shadow);
     613                 :            : int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
     614                 :            : void delete_from_page_cache_batch(struct address_space *mapping,
     615                 :            :                                   struct pagevec *pvec);
     616                 :            : 
     617                 :            : /*
     618                 :            :  * Like add_to_page_cache_locked, but used to add newly allocated pages:
     619                 :            :  * the page is new, so we can just run __SetPageLocked() against it.
     620                 :            :  */
     621                 :            : static inline int add_to_page_cache(struct page *page,
     622                 :            :                 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
     623                 :            : {
     624                 :            :         int error;
     625                 :            : 
     626                 :            :         __SetPageLocked(page);
     627                 :            :         error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
     628                 :            :         if (unlikely(error))
     629                 :            :                 __ClearPageLocked(page);
     630                 :            :         return error;
     631                 :            : }
     632                 :            : 
     633                 :            : static inline unsigned long dir_pages(struct inode *inode)
     634                 :            : {
     635                 :            :         return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
     636                 :            :                                PAGE_SHIFT;
     637                 :            : }
     638                 :            : 
     639                 :            : #endif /* _LINUX_PAGEMAP_H */
    

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