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-rw-r--r--mm/shmem.c782
1 files changed, 84 insertions, 698 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 5cc21f8b4cd3..5574b00ca771 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -66,37 +66,9 @@ static struct vfsmount *shm_mnt;
#include <asm/div64.h>
#include <asm/pgtable.h>
-/*
- * The maximum size of a shmem/tmpfs file is limited by the maximum size of
- * its triple-indirect swap vector - see illustration at shmem_swp_entry().
- *
- * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
- * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
- * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
- * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
- *
- * We use / and * instead of shifts in the definitions below, so that the swap
- * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
- */
-#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
-#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
-
-#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
-#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
-
-#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
-#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
-
#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
-/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
-#define SHMEM_PAGEIN VM_READ
-#define SHMEM_TRUNCATE VM_WRITE
-
-/* Definition to limit shmem_truncate's steps between cond_rescheds */
-#define LATENCY_LIMIT 64
-
/* Pretend that each entry is of this size in directory's i_size */
#define BOGO_DIRENT_SIZE 20
@@ -107,7 +79,7 @@ struct shmem_xattr {
char value[0];
};
-/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
+/* Flag allocation requirements to shmem_getpage */
enum sgp_type {
SGP_READ, /* don't exceed i_size, don't allocate page */
SGP_CACHE, /* don't exceed i_size, may allocate page */
@@ -137,56 +109,6 @@ static inline int shmem_getpage(struct inode *inode, pgoff_t index,
mapping_gfp_mask(inode->i_mapping), fault_type);
}
-static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
-{
- /*
- * The above definition of ENTRIES_PER_PAGE, and the use of
- * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
- * might be reconsidered if it ever diverges from PAGE_SIZE.
- *
- * Mobility flags are masked out as swap vectors cannot move
- */
- return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
- PAGE_CACHE_SHIFT-PAGE_SHIFT);
-}
-
-static inline void shmem_dir_free(struct page *page)
-{
- __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
-}
-
-static struct page **shmem_dir_map(struct page *page)
-{
- return (struct page **)kmap_atomic(page, KM_USER0);
-}
-
-static inline void shmem_dir_unmap(struct page **dir)
-{
- kunmap_atomic(dir, KM_USER0);
-}
-
-static swp_entry_t *shmem_swp_map(struct page *page)
-{
- return (swp_entry_t *)kmap_atomic(page, KM_USER1);
-}
-
-static inline void shmem_swp_balance_unmap(void)
-{
- /*
- * When passing a pointer to an i_direct entry, to code which
- * also handles indirect entries and so will shmem_swp_unmap,
- * we must arrange for the preempt count to remain in balance.
- * What kmap_atomic of a lowmem page does depends on config
- * and architecture, so pretend to kmap_atomic some lowmem page.
- */
- (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
-}
-
-static inline void shmem_swp_unmap(swp_entry_t *entry)
-{
- kunmap_atomic(entry, KM_USER1);
-}
-
static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
{
return sb->s_fs_info;
@@ -303,468 +225,56 @@ static void shmem_recalc_inode(struct inode *inode)
}
}
-/**
- * shmem_swp_entry - find the swap vector position in the info structure
- * @info: info structure for the inode
- * @index: index of the page to find
- * @page: optional page to add to the structure. Has to be preset to
- * all zeros
- *
- * If there is no space allocated yet it will return NULL when
- * page is NULL, else it will use the page for the needed block,
- * setting it to NULL on return to indicate that it has been used.
- *
- * The swap vector is organized the following way:
- *
- * There are SHMEM_NR_DIRECT entries directly stored in the
- * shmem_inode_info structure. So small files do not need an addional
- * allocation.
- *
- * For pages with index > SHMEM_NR_DIRECT there is the pointer
- * i_indirect which points to a page which holds in the first half
- * doubly indirect blocks, in the second half triple indirect blocks:
- *
- * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
- * following layout (for SHMEM_NR_DIRECT == 16):
- *
- * i_indirect -> dir --> 16-19
- * | +-> 20-23
- * |
- * +-->dir2 --> 24-27
- * | +-> 28-31
- * | +-> 32-35
- * | +-> 36-39
- * |
- * +-->dir3 --> 40-43
- * +-> 44-47
- * +-> 48-51
- * +-> 52-55
- */
-static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
-{
- unsigned long offset;
- struct page **dir;
- struct page *subdir;
-
- if (index < SHMEM_NR_DIRECT) {
- shmem_swp_balance_unmap();
- return info->i_direct+index;
- }
- if (!info->i_indirect) {
- if (page) {
- info->i_indirect = *page;
- *page = NULL;
- }
- return NULL; /* need another page */
- }
-
- index -= SHMEM_NR_DIRECT;
- offset = index % ENTRIES_PER_PAGE;
- index /= ENTRIES_PER_PAGE;
- dir = shmem_dir_map(info->i_indirect);
-
- if (index >= ENTRIES_PER_PAGE/2) {
- index -= ENTRIES_PER_PAGE/2;
- dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
- index %= ENTRIES_PER_PAGE;
- subdir = *dir;
- if (!subdir) {
- if (page) {
- *dir = *page;
- *page = NULL;
- }
- shmem_dir_unmap(dir);
- return NULL; /* need another page */
- }
- shmem_dir_unmap(dir);
- dir = shmem_dir_map(subdir);
- }
-
- dir += index;
- subdir = *dir;
- if (!subdir) {
- if (!page || !(subdir = *page)) {
- shmem_dir_unmap(dir);
- return NULL; /* need a page */
- }
- *dir = subdir;
- *page = NULL;
- }
- shmem_dir_unmap(dir);
- return shmem_swp_map(subdir) + offset;
-}
-
-static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
+static void shmem_put_swap(struct shmem_inode_info *info, pgoff_t index,
+ swp_entry_t swap)
{
- long incdec = value? 1: -1;
-
- entry->val = value;
- info->swapped += incdec;
- if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
- struct page *page = kmap_atomic_to_page(entry);
- set_page_private(page, page_private(page) + incdec);
- }
-}
-
-/**
- * shmem_swp_alloc - get the position of the swap entry for the page.
- * @info: info structure for the inode
- * @index: index of the page to find
- * @sgp: check and recheck i_size? skip allocation?
- * @gfp: gfp mask to use for any page allocation
- *
- * If the entry does not exist, allocate it.
- */
-static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info,
- unsigned long index, enum sgp_type sgp, gfp_t gfp)
-{
- struct inode *inode = &info->vfs_inode;
- struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
- struct page *page = NULL;
- swp_entry_t *entry;
-
- if (sgp != SGP_WRITE &&
- ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
- return ERR_PTR(-EINVAL);
-
- while (!(entry = shmem_swp_entry(info, index, &page))) {
- if (sgp == SGP_READ)
- return shmem_swp_map(ZERO_PAGE(0));
- /*
- * Test used_blocks against 1 less max_blocks, since we have 1 data
- * page (and perhaps indirect index pages) yet to allocate:
- * a waste to allocate index if we cannot allocate data.
- */
- if (sbinfo->max_blocks) {
- if (percpu_counter_compare(&sbinfo->used_blocks,
- sbinfo->max_blocks - 1) >= 0)
- return ERR_PTR(-ENOSPC);
- percpu_counter_inc(&sbinfo->used_blocks);
- inode->i_blocks += BLOCKS_PER_PAGE;
- }
-
- spin_unlock(&info->lock);
- page = shmem_dir_alloc(gfp);
- spin_lock(&info->lock);
-
- if (!page) {
- shmem_free_blocks(inode, 1);
- return ERR_PTR(-ENOMEM);
- }
- if (sgp != SGP_WRITE &&
- ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
- entry = ERR_PTR(-EINVAL);
- break;
- }
- if (info->next_index <= index)
- info->next_index = index + 1;
- }
- if (page) {
- /* another task gave its page, or truncated the file */
- shmem_free_blocks(inode, 1);
- shmem_dir_free(page);
- }
- if (info->next_index <= index && !IS_ERR(entry))
- info->next_index = index + 1;
- return entry;
-}
-
-/**
- * shmem_free_swp - free some swap entries in a directory
- * @dir: pointer to the directory
- * @edir: pointer after last entry of the directory
- * @punch_lock: pointer to spinlock when needed for the holepunch case
- */
-static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
- spinlock_t *punch_lock)
-{
- spinlock_t *punch_unlock = NULL;
- swp_entry_t *ptr;
- int freed = 0;
-
- for (ptr = dir; ptr < edir; ptr++) {
- if (ptr->val) {
- if (unlikely(punch_lock)) {
- punch_unlock = punch_lock;
- punch_lock = NULL;
- spin_lock(punch_unlock);
- if (!ptr->val)
- continue;
- }
- free_swap_and_cache(*ptr);
- *ptr = (swp_entry_t){0};
- freed++;
- }
- }
- if (punch_unlock)
- spin_unlock(punch_unlock);
- return freed;
-}
-
-static int shmem_map_and_free_swp(struct page *subdir, int offset,
- int limit, struct page ***dir, spinlock_t *punch_lock)
-{
- swp_entry_t *ptr;
- int freed = 0;
-
- ptr = shmem_swp_map(subdir);
- for (; offset < limit; offset += LATENCY_LIMIT) {
- int size = limit - offset;
- if (size > LATENCY_LIMIT)
- size = LATENCY_LIMIT;
- freed += shmem_free_swp(ptr+offset, ptr+offset+size,
- punch_lock);
- if (need_resched()) {
- shmem_swp_unmap(ptr);
- if (*dir) {
- shmem_dir_unmap(*dir);
- *dir = NULL;
- }
- cond_resched();
- ptr = shmem_swp_map(subdir);
- }
- }
- shmem_swp_unmap(ptr);
- return freed;
+ if (index < SHMEM_NR_DIRECT)
+ info->i_direct[index] = swap;
}
-static void shmem_free_pages(struct list_head *next)
+static swp_entry_t shmem_get_swap(struct shmem_inode_info *info, pgoff_t index)
{
- struct page *page;
- int freed = 0;
-
- do {
- page = container_of(next, struct page, lru);
- next = next->next;
- shmem_dir_free(page);
- freed++;
- if (freed >= LATENCY_LIMIT) {
- cond_resched();
- freed = 0;
- }
- } while (next);
+ return (index < SHMEM_NR_DIRECT) ?
+ info->i_direct[index] : (swp_entry_t){0};
}
-void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
+void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
{
+ struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
- unsigned long idx;
- unsigned long size;
- unsigned long limit;
- unsigned long stage;
- unsigned long diroff;
- struct page **dir;
- struct page *topdir;
- struct page *middir;
- struct page *subdir;
- swp_entry_t *ptr;
- LIST_HEAD(pages_to_free);
- long nr_pages_to_free = 0;
- long nr_swaps_freed = 0;
- int offset;
- int freed;
- int punch_hole;
- spinlock_t *needs_lock;
- spinlock_t *punch_lock;
- unsigned long upper_limit;
+ pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ pgoff_t end = (lend >> PAGE_CACHE_SHIFT);
+ pgoff_t index;
+ swp_entry_t swap;
- truncate_inode_pages_range(inode->i_mapping, start, end);
+ truncate_inode_pages_range(mapping, lstart, lend);
- inode->i_ctime = inode->i_mtime = CURRENT_TIME;
- idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
- if (idx >= info->next_index)
- return;
+ if (end > SHMEM_NR_DIRECT)
+ end = SHMEM_NR_DIRECT;
spin_lock(&info->lock);
- info->flags |= SHMEM_TRUNCATE;
- if (likely(end == (loff_t) -1)) {
- limit = info->next_index;
- upper_limit = SHMEM_MAX_INDEX;
- info->next_index = idx;
- needs_lock = NULL;
- punch_hole = 0;
- } else {
- if (end + 1 >= inode->i_size) { /* we may free a little more */
- limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
- PAGE_CACHE_SHIFT;
- upper_limit = SHMEM_MAX_INDEX;
- } else {
- limit = (end + 1) >> PAGE_CACHE_SHIFT;
- upper_limit = limit;
- }
- needs_lock = &info->lock;
- punch_hole = 1;
- }
-
- topdir = info->i_indirect;
- if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
- info->i_indirect = NULL;
- nr_pages_to_free++;
- list_add(&topdir->lru, &pages_to_free);
- }
- spin_unlock(&info->lock);
-
- if (info->swapped && idx < SHMEM_NR_DIRECT) {
- ptr = info->i_direct;
- size = limit;
- if (size > SHMEM_NR_DIRECT)
- size = SHMEM_NR_DIRECT;
- nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
- }
-
- /*
- * If there are no indirect blocks or we are punching a hole
- * below indirect blocks, nothing to be done.
- */
- if (!topdir || limit <= SHMEM_NR_DIRECT)
- goto done2;
-
- /*
- * The truncation case has already dropped info->lock, and we're safe
- * because i_size and next_index have already been lowered, preventing
- * access beyond. But in the punch_hole case, we still need to take
- * the lock when updating the swap directory, because there might be
- * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
- * shmem_writepage. However, whenever we find we can remove a whole
- * directory page (not at the misaligned start or end of the range),
- * we first NULLify its pointer in the level above, and then have no
- * need to take the lock when updating its contents: needs_lock and
- * punch_lock (either pointing to info->lock or NULL) manage this.
- */
-
- upper_limit -= SHMEM_NR_DIRECT;
- limit -= SHMEM_NR_DIRECT;
- idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
- offset = idx % ENTRIES_PER_PAGE;
- idx -= offset;
-
- dir = shmem_dir_map(topdir);
- stage = ENTRIES_PER_PAGEPAGE/2;
- if (idx < ENTRIES_PER_PAGEPAGE/2) {
- middir = topdir;
- diroff = idx/ENTRIES_PER_PAGE;
- } else {
- dir += ENTRIES_PER_PAGE/2;
- dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
- while (stage <= idx)
- stage += ENTRIES_PER_PAGEPAGE;
- middir = *dir;
- if (*dir) {
- diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
- ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
- if (!diroff && !offset && upper_limit >= stage) {
- if (needs_lock) {
- spin_lock(needs_lock);
- *dir = NULL;
- spin_unlock(needs_lock);
- needs_lock = NULL;
- } else
- *dir = NULL;
- nr_pages_to_free++;
- list_add(&middir->lru, &pages_to_free);
- }
- shmem_dir_unmap(dir);
- dir = shmem_dir_map(middir);
- } else {
- diroff = 0;
- offset = 0;
- idx = stage;
+ for (index = start; index < end; index++) {
+ swap = shmem_get_swap(info, index);
+ if (swap.val) {
+ free_swap_and_cache(swap);
+ shmem_put_swap(info, index, (swp_entry_t){0});
+ info->swapped--;
}
}
- for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
- if (unlikely(idx == stage)) {
- shmem_dir_unmap(dir);
- dir = shmem_dir_map(topdir) +
- ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
- while (!*dir) {
- dir++;
- idx += ENTRIES_PER_PAGEPAGE;
- if (idx >= limit)
- goto done1;
- }
- stage = idx + ENTRIES_PER_PAGEPAGE;
- middir = *dir;
- if (punch_hole)
- needs_lock = &info->lock;
- if (upper_limit >= stage) {
- if (needs_lock) {
- spin_lock(needs_lock);
- *dir = NULL;
- spin_unlock(needs_lock);
- needs_lock = NULL;
- } else
- *dir = NULL;
- nr_pages_to_free++;
- list_add(&middir->lru, &pages_to_free);
- }
- shmem_dir_unmap(dir);
- cond_resched();
- dir = shmem_dir_map(middir);
- diroff = 0;
- }
- punch_lock = needs_lock;
- subdir = dir[diroff];
- if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
- if (needs_lock) {
- spin_lock(needs_lock);
- dir[diroff] = NULL;
- spin_unlock(needs_lock);
- punch_lock = NULL;
- } else
- dir[diroff] = NULL;
- nr_pages_to_free++;
- list_add(&subdir->lru, &pages_to_free);
- }
- if (subdir && page_private(subdir) /* has swap entries */) {
- size = limit - idx;
- if (size > ENTRIES_PER_PAGE)
- size = ENTRIES_PER_PAGE;
- freed = shmem_map_and_free_swp(subdir,
- offset, size, &dir, punch_lock);
- if (!dir)
- dir = shmem_dir_map(middir);
- nr_swaps_freed += freed;
- if (offset || punch_lock) {
- spin_lock(&info->lock);
- set_page_private(subdir,
- page_private(subdir) - freed);
- spin_unlock(&info->lock);
- } else
- BUG_ON(page_private(subdir) != freed);
- }
- offset = 0;
- }
-done1:
- shmem_dir_unmap(dir);
-done2:
- if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
+ if (mapping->nrpages) {
+ spin_unlock(&info->lock);
/*
- * Call truncate_inode_pages again: racing shmem_unuse_inode
- * may have swizzled a page in from swap since
- * truncate_pagecache or generic_delete_inode did it, before we
- * lowered next_index. Also, though shmem_getpage checks
- * i_size before adding to cache, no recheck after: so fix the
- * narrow window there too.
+ * A page may have meanwhile sneaked in from swap.
*/
- truncate_inode_pages_range(inode->i_mapping, start, end);
+ truncate_inode_pages_range(mapping, lstart, lend);
+ spin_lock(&info->lock);
}
- spin_lock(&info->lock);
- info->flags &= ~SHMEM_TRUNCATE;
- info->swapped -= nr_swaps_freed;
- if (nr_pages_to_free)
- shmem_free_blocks(inode, nr_pages_to_free);
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
- /*
- * Empty swap vector directory pages to be freed?
- */
- if (!list_empty(&pages_to_free)) {
- pages_to_free.prev->next = NULL;
- shmem_free_pages(pages_to_free.next);
- }
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
}
EXPORT_SYMBOL_GPL(shmem_truncate_range);
@@ -797,19 +307,6 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
if (page)
unlock_page(page);
}
- /*
- * Reset SHMEM_PAGEIN flag so that shmem_truncate can
- * detect if any pages might have been added to cache
- * after truncate_inode_pages. But we needn't bother
- * if it's being fully truncated to zero-length: the
- * nrpages check is efficient enough in that case.
- */
- if (newsize) {
- struct shmem_inode_info *info = SHMEM_I(inode);
- spin_lock(&info->lock);
- info->flags &= ~SHMEM_PAGEIN;
- spin_unlock(&info->lock);
- }
}
if (newsize != oldsize) {
i_size_write(inode, newsize);
@@ -859,106 +356,28 @@ static void shmem_evict_inode(struct inode *inode)
end_writeback(inode);
}
-static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
-{
- swp_entry_t *ptr;
-
- for (ptr = dir; ptr < edir; ptr++) {
- if (ptr->val == entry.val)
- return ptr - dir;
- }
- return -1;
-}
-
static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
{
- struct address_space *mapping;
+ struct address_space *mapping = info->vfs_inode.i_mapping;
unsigned long idx;
- unsigned long size;
- unsigned long limit;
- unsigned long stage;
- struct page **dir;
- struct page *subdir;
- swp_entry_t *ptr;
- int offset;
int error;
- idx = 0;
- ptr = info->i_direct;
- spin_lock(&info->lock);
- if (!info->swapped) {
- list_del_init(&info->swaplist);
- goto lost2;
- }
- limit = info->next_index;
- size = limit;
- if (size > SHMEM_NR_DIRECT)
- size = SHMEM_NR_DIRECT;
- offset = shmem_find_swp(entry, ptr, ptr+size);
- if (offset >= 0) {
- shmem_swp_balance_unmap();
- goto found;
- }
- if (!info->i_indirect)
- goto lost2;
-
- dir = shmem_dir_map(info->i_indirect);
- stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
-
- for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
- if (unlikely(idx == stage)) {
- shmem_dir_unmap(dir-1);
- if (cond_resched_lock(&info->lock)) {
- /* check it has not been truncated */
- if (limit > info->next_index) {
- limit = info->next_index;
- if (idx >= limit)
- goto lost2;
- }
- }
- dir = shmem_dir_map(info->i_indirect) +
- ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
- while (!*dir) {
- dir++;
- idx += ENTRIES_PER_PAGEPAGE;
- if (idx >= limit)
- goto lost1;
- }
- stage = idx + ENTRIES_PER_PAGEPAGE;
- subdir = *dir;
- shmem_dir_unmap(dir);
- dir = shmem_dir_map(subdir);
- }
- subdir = *dir;
- if (subdir && page_private(subdir)) {
- ptr = shmem_swp_map(subdir);
- size = limit - idx;
- if (size > ENTRIES_PER_PAGE)
- size = ENTRIES_PER_PAGE;
- offset = shmem_find_swp(entry, ptr, ptr+size);
- shmem_swp_unmap(ptr);
- if (offset >= 0) {
- shmem_dir_unmap(dir);
- ptr = shmem_swp_map(subdir);
- goto found;
- }
- }
- }
-lost1:
- shmem_dir_unmap(dir-1);
-lost2:
- spin_unlock(&info->lock);
+ for (idx = 0; idx < SHMEM_NR_DIRECT; idx++)
+ if (shmem_get_swap(info, idx).val == entry.val)
+ goto found;
return 0;
found:
- idx += offset;
- ptr += offset;
+ spin_lock(&info->lock);
+ if (shmem_get_swap(info, idx).val != entry.val) {
+ spin_unlock(&info->lock);
+ return 0;
+ }
/*
* Move _head_ to start search for next from here.
* But be careful: shmem_evict_inode checks list_empty without taking
* mutex, and there's an instant in list_move_tail when info->swaplist
- * would appear empty, if it were the only one on shmem_swaplist. We
- * could avoid doing it if inode NULL; or use this minor optimization.
+ * would appear empty, if it were the only one on shmem_swaplist.
*/
if (shmem_swaplist.next != &info->swaplist)
list_move_tail(&shmem_swaplist, &info->swaplist);
@@ -968,19 +387,17 @@ found:
* but also to hold up shmem_evict_inode(): so inode cannot be freed
* beneath us (pagelock doesn't help until the page is in pagecache).
*/
- mapping = info->vfs_inode.i_mapping;
error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT);
/* which does mem_cgroup_uncharge_cache_page on error */
if (error != -ENOMEM) {
delete_from_swap_cache(page);
set_page_dirty(page);
- info->flags |= SHMEM_PAGEIN;
- shmem_swp_set(info, ptr, 0);
+ shmem_put_swap(info, idx, (swp_entry_t){0});
+ info->swapped--;
swap_free(entry);
error = 1; /* not an error, but entry was found */
}
- shmem_swp_unmap(ptr);
spin_unlock(&info->lock);
return error;
}
@@ -1017,7 +434,14 @@ int shmem_unuse(swp_entry_t entry, struct page *page)
mutex_lock(&shmem_swaplist_mutex);
list_for_each_safe(p, next, &shmem_swaplist) {
info = list_entry(p, struct shmem_inode_info, swaplist);
- found = shmem_unuse_inode(info, entry, page);
+ if (!info->swapped) {
+ spin_lock(&info->lock);
+ if (!info->swapped)
+ list_del_init(&info->swaplist);
+ spin_unlock(&info->lock);
+ }
+ if (info->swapped)
+ found = shmem_unuse_inode(info, entry, page);
cond_resched();
if (found)
break;
@@ -1041,7 +465,7 @@ out:
static int shmem_writepage(struct page *page, struct writeback_control *wbc)
{
struct shmem_inode_info *info;
- swp_entry_t *entry, swap;
+ swp_entry_t swap, oswap;
struct address_space *mapping;
unsigned long index;
struct inode *inode;
@@ -1067,6 +491,15 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
goto redirty;
}
+
+ /*
+ * Just for this patch, we have a toy implementation,
+ * which can swap out only the first SHMEM_NR_DIRECT pages:
+ * for simple demonstration of where we need to think about swap.
+ */
+ if (index >= SHMEM_NR_DIRECT)
+ goto redirty;
+
swap = get_swap_page();
if (!swap.val)
goto redirty;
@@ -1087,22 +520,19 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
spin_lock(&info->lock);
mutex_unlock(&shmem_swaplist_mutex);
- if (index >= info->next_index) {
- BUG_ON(!(info->flags & SHMEM_TRUNCATE));
- goto unlock;
- }
- entry = shmem_swp_entry(info, index, NULL);
- if (entry->val) {
+ oswap = shmem_get_swap(info, index);
+ if (oswap.val) {
WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
- free_swap_and_cache(*entry);
- shmem_swp_set(info, entry, 0);
+ free_swap_and_cache(oswap);
+ shmem_put_swap(info, index, (swp_entry_t){0});
+ info->swapped--;
}
shmem_recalc_inode(inode);
if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
delete_from_page_cache(page);
- shmem_swp_set(info, entry, swap.val);
- shmem_swp_unmap(entry);
+ shmem_put_swap(info, index, swap);
+ info->swapped++;
swap_shmem_alloc(swap);
spin_unlock(&info->lock);
BUG_ON(page_mapped(page));
@@ -1110,13 +540,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
return 0;
}
- shmem_swp_unmap(entry);
-unlock:
spin_unlock(&info->lock);
- /*
- * add_to_swap_cache() doesn't return -EEXIST, so we can safely
- * clear SWAP_HAS_CACHE flag.
- */
swapcache_free(swap, NULL);
redirty:
set_page_dirty(page);
@@ -1230,12 +654,10 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t idx,
struct shmem_sb_info *sbinfo;
struct page *page;
struct page *prealloc_page = NULL;
- swp_entry_t *entry;
swp_entry_t swap;
int error;
- int ret;
- if (idx >= SHMEM_MAX_INDEX)
+ if (idx > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
return -EFBIG;
repeat:
page = find_lock_page(mapping, idx);
@@ -1272,37 +694,22 @@ repeat:
spin_lock(&info->lock);
shmem_recalc_inode(inode);
- entry = shmem_swp_alloc(info, idx, sgp, gfp);
- if (IS_ERR(entry)) {
- spin_unlock(&info->lock);
- error = PTR_ERR(entry);
- goto out;
- }
- swap = *entry;
-
+ swap = shmem_get_swap(info, idx);
if (swap.val) {
/* Look it up and read it in.. */
page = lookup_swap_cache(swap);
if (!page) {
- shmem_swp_unmap(entry);
spin_unlock(&info->lock);
/* here we actually do the io */
if (fault_type)
*fault_type |= VM_FAULT_MAJOR;
page = shmem_swapin(swap, gfp, info, idx);
if (!page) {
- spin_lock(&info->lock);
- entry = shmem_swp_alloc(info, idx, sgp, gfp);
- if (IS_ERR(entry))
- error = PTR_ERR(entry);
- else {
- if (entry->val == swap.val)
- error = -ENOMEM;
- shmem_swp_unmap(entry);
- }
- spin_unlock(&info->lock);
- if (error)
+ swp_entry_t nswap = shmem_get_swap(info, idx);
+ if (nswap.val == swap.val) {
+ error = -ENOMEM;
goto out;
+ }
goto repeat;
}
wait_on_page_locked(page);
@@ -1312,14 +719,12 @@ repeat:
/* We have to do this with page locked to prevent races */
if (!trylock_page(page)) {
- shmem_swp_unmap(entry);
spin_unlock(&info->lock);
wait_on_page_locked(page);
page_cache_release(page);
goto repeat;
}
if (PageWriteback(page)) {
- shmem_swp_unmap(entry);
spin_unlock(&info->lock);
wait_on_page_writeback(page);
unlock_page(page);
@@ -1327,7 +732,6 @@ repeat:
goto repeat;
}
if (!PageUptodate(page)) {
- shmem_swp_unmap(entry);
spin_unlock(&info->lock);
unlock_page(page);
page_cache_release(page);
@@ -1338,7 +742,6 @@ repeat:
error = add_to_page_cache_locked(page, mapping,
idx, GFP_NOWAIT);
if (error) {
- shmem_swp_unmap(entry);
spin_unlock(&info->lock);
if (error == -ENOMEM) {
/*
@@ -1358,16 +761,14 @@ repeat:
goto repeat;
}
- info->flags |= SHMEM_PAGEIN;
- shmem_swp_set(info, entry, 0);
- shmem_swp_unmap(entry);
delete_from_swap_cache(page);
+ shmem_put_swap(info, idx, (swp_entry_t){0});
+ info->swapped--;
spin_unlock(&info->lock);
set_page_dirty(page);
swap_free(swap);
} else if (sgp == SGP_READ) {
- shmem_swp_unmap(entry);
page = find_get_page(mapping, idx);
if (page && !trylock_page(page)) {
spin_unlock(&info->lock);
@@ -1378,7 +779,6 @@ repeat:
spin_unlock(&info->lock);
} else if (prealloc_page) {
- shmem_swp_unmap(entry);
sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks) {
if (percpu_counter_compare(&sbinfo->used_blocks,
@@ -1393,34 +793,24 @@ repeat:
page = prealloc_page;
prealloc_page = NULL;
- entry = shmem_swp_alloc(info, idx, sgp, gfp);
- if (IS_ERR(entry))
- error = PTR_ERR(entry);
- else {
- swap = *entry;
- shmem_swp_unmap(entry);
- }
- ret = error || swap.val;
- if (ret)
+ swap = shmem_get_swap(info, idx);
+ if (swap.val)
mem_cgroup_uncharge_cache_page(page);
else
- ret = add_to_page_cache_lru(page, mapping,
+ error = add_to_page_cache_lru(page, mapping,
idx, GFP_NOWAIT);
/*
* At add_to_page_cache_lru() failure,
* uncharge will be done automatically.
*/
- if (ret) {
+ if (swap.val || error) {
shmem_unacct_blocks(info->flags, 1);
shmem_free_blocks(inode, 1);
spin_unlock(&info->lock);
page_cache_release(page);
- if (error)
- goto out;
goto repeat;
}
- info->flags |= SHMEM_PAGEIN;
info->alloced++;
spin_unlock(&info->lock);
clear_highpage(page);
@@ -2627,7 +2017,7 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
goto failed;
sbinfo->free_inodes = sbinfo->max_inodes;
- sb->s_maxbytes = SHMEM_MAX_BYTES;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = TMPFS_MAGIC;
@@ -2863,7 +2253,7 @@ out4:
void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
struct page **pagep, swp_entry_t *ent)
{
- swp_entry_t entry = { .val = 0 }, *ptr;
+ swp_entry_t entry = { .val = 0 };
struct page *page = NULL;
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -2871,16 +2261,13 @@ void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
goto out;
spin_lock(&info->lock);
- ptr = shmem_swp_entry(info, pgoff, NULL);
#ifdef CONFIG_SWAP
- if (ptr && ptr->val) {
- entry.val = ptr->val;
+ entry = shmem_get_swap(info, pgoff);
+ if (entry.val)
page = find_get_page(&swapper_space, entry.val);
- } else
+ else
#endif
page = find_get_page(inode->i_mapping, pgoff);
- if (ptr)
- shmem_swp_unmap(ptr);
spin_unlock(&info->lock);
out:
*pagep = page;
@@ -2963,7 +2350,6 @@ out:
#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
#define shmem_acct_size(flags, size) 0
#define shmem_unacct_size(flags, size) do {} while (0)
-#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
#endif /* CONFIG_SHMEM */
@@ -2987,7 +2373,7 @@ struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags
if (IS_ERR(shm_mnt))
return (void *)shm_mnt;
- if (size < 0 || size > SHMEM_MAX_BYTES)
+ if (size < 0 || size > MAX_LFS_FILESIZE)
return ERR_PTR(-EINVAL);
if (shmem_acct_size(flags, size))
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 10:19:49 +0000