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btrfs: Use filemap_range_has_page()

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The current implementation of btrfs_page_exists_in_range() gives the
wrong answer if the workingset code has stored a shadow entry in the
page cache.  The filemap_range_has_page() function does not have this
problem, and it's shared code, so use it instead.

eigned-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Matthew Wilcox 2018-03-06 11:23:16 -08:00 committed by David Sterba
parent 4759700a71
commit 965aab1cfc
2 changed files with 5 additions and 71 deletions
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6
fs/btrfs/btrfs_inode.h
View file

@ -364,6 +364,10 @@ static inline void btrfs_print_data_csum_error(struct btrfs_inode *inode,
logical_start, csum, csum_expected, mirror_num);
}
bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end);
static inline bool btrfs_page_exists_in_range(struct inode *inode,
loff_t start, loff_t end)
{
return filemap_range_has_page(inode->i_mapping, start, end);
}
#endif

70
fs/btrfs/inode.c
View file

@ -7464,76 +7464,6 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
return ret;
}
bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end)
{
struct radix_tree_root *root = &inode->i_mapping->page_tree;
bool found = false;
void **pagep = NULL;
struct page *page = NULL;
unsigned long start_idx;
unsigned long end_idx;
start_idx = start >> PAGE_SHIFT;
/*
* end is the last byte in the last page. end == start is legal
*/
end_idx = end >> PAGE_SHIFT;
rcu_read_lock();
/* Most of the code in this while loop is lifted from
* find_get_page. It's been modified to begin searching from a
* page and return just the first page found in that range. If the
* found idx is less than or equal to the end idx then we know that
* a page exists. If no pages are found or if those pages are
* outside of the range then we're fine (yay!) */
while (page == NULL &&
radix_tree_gang_lookup_slot(root, &pagep, NULL, start_idx, 1)) {
page = radix_tree_deref_slot(pagep);
if (unlikely(!page))
break;
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page)) {
page = NULL;
continue;
}
/*
* Otherwise, shmem/tmpfs must be storing a swap entry
* here as an exceptional entry: so return it without
* attempting to raise page count.
*/
page = NULL;
break; /* TODO: Is this relevant for this use case? */
}
if (!page_cache_get_speculative(page)) {
page = NULL;
continue;
}
/*
* Has the page moved?
* This is part of the lockless pagecache protocol. See
* include/linux/pagemap.h for details.
*/
if (unlikely(page != *pagep)) {
put_page(page);
page = NULL;
}
}
if (page) {
if (page->index <= end_idx)
found = true;
put_page(page);
}
rcu_read_unlock();
return found;
}
static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
struct extent_state **cached_state, int writing)
{