vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
}
-static struct super_operations shmem_ops;
+static const struct super_operations shmem_ops;
static const struct address_space_operations shmem_aops;
static const struct file_operations shmem_file_operations;
-static struct inode_operations shmem_inode_operations;
-static struct inode_operations shmem_dir_inode_operations;
-static struct inode_operations shmem_special_inode_operations;
+static const struct inode_operations shmem_inode_operations;
+static const struct inode_operations shmem_dir_inode_operations;
+static const struct inode_operations shmem_special_inode_operations;
static struct vm_operations_struct shmem_vm_ops;
static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
/*
* shmem_free_swp - free some swap entries in a directory
*
- * @dir: pointer to the directory
- * @edir: pointer after last entry of the 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)
+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)
+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;
int size = limit - offset;
if (size > LATENCY_LIMIT)
size = LATENCY_LIMIT;
- freed += shmem_free_swp(ptr+offset, ptr+offset+size);
+ freed += shmem_free_swp(ptr+offset, ptr+offset+size,
+ punch_lock);
if (need_resched()) {
shmem_swp_unmap(ptr);
if (*dir) {
long nr_swaps_freed = 0;
int offset;
int freed;
- int punch_hole = 0;
+ int punch_hole;
+ spinlock_t *needs_lock;
+ spinlock_t *punch_lock;
+ unsigned long upper_limit;
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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 {
- limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
- if (limit > info->next_index)
- limit = info->next_index;
+ 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;
}
size = limit;
if (size > SHMEM_NR_DIRECT)
size = SHMEM_NR_DIRECT;
- nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
+ 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 || (punch_hole && (limit <= SHMEM_NR_DIRECT)))
+ if (!topdir || limit <= SHMEM_NR_DIRECT)
goto done2;
- BUG_ON(limit <= SHMEM_NR_DIRECT);
+ /*
+ * 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;
if (*dir) {
diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
- if (!diroff && !offset) {
- *dir = NULL;
+ 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);
}
}
stage = idx + ENTRIES_PER_PAGEPAGE;
middir = *dir;
- *dir = NULL;
- nr_pages_to_free++;
- list_add(&middir->lru, &pages_to_free);
+ 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 && page_private(subdir)) {
+ 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);
+ offset, size, &dir, punch_lock);
if (!dir)
dir = shmem_dir_map(middir);
nr_swaps_freed += freed;
- if (offset)
+ if (offset || punch_lock) {
spin_lock(&info->lock);
- set_page_private(subdir, page_private(subdir) - freed);
- if (offset)
+ set_page_private(subdir,
+ page_private(subdir) - freed);
spin_unlock(&info->lock);
- if (!punch_hole)
- BUG_ON(page_private(subdir) > offset);
- }
- if (offset)
- offset = 0;
- else if (subdir && !page_private(subdir)) {
- dir[diroff] = NULL;
- nr_pages_to_free++;
- list_add(&subdir->lru, &pages_to_free);
+ } else
+ BUG_ON(page_private(subdir) != freed);
}
+ offset = 0;
}
done1:
shmem_dir_unmap(dir);
* 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.
+ *
+ * Recalling truncate_inode_pages_range and unmap_mapping_range
+ * every time for punch_hole (which never got a chance to clear
+ * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
+ * yet hardly ever necessary: try to optimize them out later.
*/
truncate_inode_pages_range(inode->i_mapping, start, end);
+ if (punch_hole)
+ unmap_mapping_range(inode->i_mapping, start,
+ end - start, 1);
}
spin_lock(&info->lock);
return error;
}
-struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
+static struct page *shmem_nopage(struct vm_area_struct *vma,
+ unsigned long address, int *type)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
struct page *page = NULL;
return retval;
}
-int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
{
file_accessed(file);
vma->vm_ops = &shmem_vm_ops;
}
#ifdef CONFIG_TMPFS
-static struct inode_operations shmem_symlink_inode_operations;
-static struct inode_operations shmem_symlink_inline_operations;
+static const struct inode_operations shmem_symlink_inode_operations;
+static const struct inode_operations shmem_symlink_inline_operations;
/*
* Normally tmpfs makes no use of shmem_prepare_write, but it
}
}
-static struct inode_operations shmem_symlink_inline_operations = {
+static const struct inode_operations shmem_symlink_inline_operations = {
.readlink = generic_readlink,
.follow_link = shmem_follow_link_inline,
};
-static struct inode_operations shmem_symlink_inode_operations = {
+static const struct inode_operations shmem_symlink_inode_operations = {
.truncate = shmem_truncate,
.readlink = generic_readlink,
.follow_link = shmem_follow_link,
static const struct address_space_operations shmem_aops = {
.writepage = shmem_writepage,
- .set_page_dirty = __set_page_dirty_nobuffers,
+ .set_page_dirty = __set_page_dirty_no_writeback,
#ifdef CONFIG_TMPFS
.prepare_write = shmem_prepare_write,
.commit_write = simple_commit_write,
#endif
};
-static struct inode_operations shmem_inode_operations = {
+static const struct inode_operations shmem_inode_operations = {
.truncate = shmem_truncate,
.setattr = shmem_notify_change,
.truncate_range = shmem_truncate_range,
};
-static struct inode_operations shmem_dir_inode_operations = {
+static const struct inode_operations shmem_dir_inode_operations = {
#ifdef CONFIG_TMPFS
.create = shmem_create,
.lookup = simple_lookup,
#endif
};
-static struct inode_operations shmem_special_inode_operations = {
+static const struct inode_operations shmem_special_inode_operations = {
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_notify_change,
.setxattr = generic_setxattr,
#endif
};
-static struct super_operations shmem_ops = {
+static const struct super_operations shmem_ops = {
.alloc_inode = shmem_alloc_inode,
.destroy_inode = shmem_destroy_inode,
#ifdef CONFIG_TMPFS
git.openpandora.org / pandora-kernel.git / blobdiff