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btrfs: Drop EXTENT_UPTODATE check in hole punching and direct locking
In these instances, we are trying to determine if a page has been accessed since we began the operation for the sake of retry. This is easily accomplished by doing a gang lookup in the page mapping radix tree, and it saves us the dependency on the flag (so that we might eventually delete it). btrfs_page_exists_in_range borrows heavily from find_get_page, replacing the radix tree look up with a gang lookup of 1, so that we can find the next highest page >= index and see if it falls into our lock range. Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Alex Gartrell <agartrell@fb.com>
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0e378df15c
commit
fc4adbff82
3 changed files with 71 additions and 7 deletions
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@ -284,4 +284,6 @@ static inline void btrfs_inode_resume_unlocked_dio(struct inode *inode)
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&BTRFS_I(inode)->runtime_flags);
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}
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bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end);
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#endif
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@ -2266,9 +2266,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
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if ((!ordered ||
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(ordered->file_offset + ordered->len <= lockstart ||
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ordered->file_offset > lockend)) &&
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!test_range_bit(&BTRFS_I(inode)->io_tree, lockstart,
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lockend, EXTENT_UPTODATE, 0,
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cached_state)) {
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!btrfs_page_exists_in_range(inode, lockstart, lockend)) {
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if (ordered)
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btrfs_put_ordered_extent(ordered);
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break;
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@ -6735,6 +6735,71 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
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return ret;
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}
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bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end)
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{
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struct radix_tree_root *root = &inode->i_mapping->page_tree;
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int found = false;
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void **pagep = NULL;
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struct page *page = NULL;
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int start_idx;
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int end_idx;
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start_idx = start >> PAGE_CACHE_SHIFT;
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/*
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* end is the last byte in the last page. end == start is legal
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*/
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end_idx = end >> PAGE_CACHE_SHIFT;
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rcu_read_lock();
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/* Most of the code in this while loop is lifted from
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* find_get_page. It's been modified to begin searching from a
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* page and return just the first page found in that range. If the
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* found idx is less than or equal to the end idx then we know that
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* a page exists. If no pages are found or if those pages are
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* outside of the range then we're fine (yay!) */
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while (page == NULL &&
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radix_tree_gang_lookup_slot(root, &pagep, NULL, start_idx, 1)) {
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page = radix_tree_deref_slot(pagep);
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if (unlikely(!page))
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break;
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if (radix_tree_exception(page)) {
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if (radix_tree_deref_retry(page))
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continue;
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/*
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* Otherwise, shmem/tmpfs must be storing a swap entry
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* here as an exceptional entry: so return it without
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* attempting to raise page count.
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*/
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break; /* TODO: Is this relevant for this use case? */
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}
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if (!page_cache_get_speculative(page))
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continue;
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/*
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* Has the page moved?
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* This is part of the lockless pagecache protocol. See
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* include/linux/pagemap.h for details.
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*/
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if (unlikely(page != *pagep)) {
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page_cache_release(page);
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page = NULL;
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}
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}
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if (page) {
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if (page->index <= end_idx)
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found = true;
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page_cache_release(page);
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}
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rcu_read_unlock();
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return found;
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}
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static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
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struct extent_state **cached_state, int writing)
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{
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@ -6759,10 +6824,9 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
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* invalidate needs to happen so that reads after a write do not
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* get stale data.
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*/
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if (!ordered && (!writing ||
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!test_range_bit(&BTRFS_I(inode)->io_tree,
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lockstart, lockend, EXTENT_UPTODATE, 0,
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*cached_state)))
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if (!ordered &&
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(!writing ||
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!btrfs_page_exists_in_range(inode, lockstart, lockend)))
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break;
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unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
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