From: Matthew Wilcox <willy@infradead.org>
To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Cc: Matthew Wilcox <mawilcox@microsoft.com>, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@redhat.com>,
Lukas Czerner <lczerner@redhat.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Christoph Hellwig <hch@lst.de>,
Goldwyn Rodrigues <rgoldwyn@suse.com>,
Nicholas Piggin <npiggin@gmail.com>,
Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>,
linux-nilfs@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
Chao Yu <yuchao0@huawei.com>,
linux-f2fs-devel@lists.sourceforge.net,
Oleg Drokin <oleg.drokin@intel.com>,
Andreas Dilger <andreas.dilger@intel.com>,
James Simmons <jsimmons@infradead.org>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH v11 18/63] page cache: Add and replace pages using the XArray
Date: Thu, 26 Apr 2018 20:24:23 -0700 [thread overview]
Message-ID: <20180427032423.GB14502@bombadil.infradead.org> (raw)
In-Reply-To: <20180414141316.7167-19-willy@infradead.org>
On Sat, Apr 14, 2018 at 07:12:31AM -0700, Matthew Wilcox wrote:
> - xa_lock_irq(&mapping->i_pages);
> - error = page_cache_tree_insert(mapping, page, shadowp);
> - radix_tree_preload_end();
> - if (unlikely(error))
> - goto err_insert;
> + do {
> + xas_lock_irq(&xas);
> + old = xas_create(&xas);
> + if (xas_error(&xas))
> + goto unlock;
> + if (xa_is_value(old)) {
> + mapping->nrexceptional--;
> + if (shadowp)
> + *shadowp = old;
> + } else if (old) {
> + xas_set_err(&xas, -EEXIST);
> + goto unlock;
> + }
> +
> + xas_store(&xas, page);
> + mapping->nrpages++;
At LSFMM, I was unable to explain in the moment why I was doing
xas_create() followed by xas_store(), rather than just calling
xas_store(). Looking at this code on my laptop, it was immediately
obvious to me -- the semantics of attempting to insert a page into the
page cache when there's already one there is to return -EEXIST.
We could also write this function this way:
+ old = xas_load(&xas);
+ if (old && !xa_is_value(old))
+ xas_set_err(&xas, -EEXIST);
+ xas_store(&xas, page);
+ if (xas_error(&xas))
+ goto unlock;
+ if (old) {
+ mapping->nrexceptional--;
+ if (shadowp)
+ *shadowp = old;
+ }
+ mapping->nrpages++;
which I think is slightly clearer. Or for those allergic to gotos, the
entire function could look like (option 3):
+ do {
+ xas_lock_irq(&xas);
+ old = xas_load(&xas);
+ if (old && !xa_is_value(old))
+ xas_set_err(&xas, -EEXIST);
+ xas_store(&xas, page);
+
+ if (!xas_error(&xas)) {
+ if (old) {
+ mapping->nrexceptional--;
+ if (shadowp)
+ *shadowp = old;
+ }
+ mapping->nrpages++;
+
+ /*
+ * hugetlb pages do not participate in
+ * page cache accounting.
+ */
+ if (!huge)
+ __inc_node_page_state(page, NR_FILE_PAGES);
+ }
+ xas_unlock_irq(&xas);
+ } while (xas_nomem(&xas, gfp_mask & ~__GFP_HIGHMEM));
next prev parent reply other threads:[~2018-04-27 3:24 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-14 14:12 [PATCH v11 00/63] Convert page cache to XArray Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 01/63] xarray: Replace exceptional entries Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 02/63] xarray: Change definition of sibling entries Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 03/63] xarray: Add definition of struct xarray Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 04/63] xarray: Define struct xa_node Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 05/63] xarray: Add documentation Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 06/63] xarray: Add xa_load Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 07/63] xarray: Add xa_get_tag, xa_set_tag and xa_clear_tag Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 08/63] xarray: Add xa_store Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 09/63] xarray: Add xa_cmpxchg and xa_insert Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 10/63] xarray: Add xa_for_each Matthew Wilcox
2018-04-20 12:00 ` Goldwyn Rodrigues
2018-04-21 1:34 ` Matthew Wilcox
2018-04-22 20:33 ` Goldwyn Rodrigues
2018-04-14 14:12 ` [PATCH v11 11/63] xarray: Add xa_extract Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 12/63] xarray: Add xa_destroy Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 13/63] xarray: Add xas_next and xas_prev Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 14/63] xarray: Add xas_create_range Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 15/63] xarray: Add MAINTAINERS entry Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 16/63] page cache: Rearrange address_space Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 17/63] page cache: Convert hole search to XArray Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 18/63] page cache: Add and replace pages using the XArray Matthew Wilcox
2018-04-27 3:24 ` Matthew Wilcox [this message]
2018-04-14 14:12 ` [PATCH v11 19/63] page cache: Convert page deletion to XArray Matthew Wilcox
2018-04-20 12:00 ` Goldwyn Rodrigues
2018-04-27 2:58 ` Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 20/63] page cache: Convert page cache lookups " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 21/63] page cache: Convert delete_batch " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 22/63] page cache: Remove stray radix comment Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 23/63] page cache: Convert filemap_range_has_page to XArray Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 24/63] mm: Convert page-writeback " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 25/63] mm: Convert workingset " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 26/63] mm: Convert truncate " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 27/63] mm: Convert add_to_swap_cache " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 28/63] mm: Convert delete_from_swap_cache " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 29/63] mm: Convert __do_page_cache_readahead " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 30/63] mm: Convert page migration " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 31/63] mm: Convert huge_memory " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 32/63] mm: Convert collapse_shmem " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 33/63] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 34/63] pagevec: Use xa_tag_t Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 35/63] shmem: Convert replace to XArray Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 36/63] shmem: Convert shmem_confirm_swap " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 37/63] shmem: Convert find_swap_entry " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 38/63] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 39/63] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 40/63] shmem: Convert shmem_free_swap " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 41/63] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 42/63] memfd: Convert shmem_wait_for_pins " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 43/63] memfd: Convert shmem_tag_pins " Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 44/63] shmem: Comment fixups Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 45/63] btrfs: Convert page cache to XArray Matthew Wilcox
2018-04-14 14:12 ` [PATCH v11 46/63] fs: Convert buffer " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 47/63] fs: Convert writeback " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 48/63] nilfs2: Convert " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 49/63] f2fs: " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 50/63] lustre: " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 51/63] dax: Fix use of zero page Matthew Wilcox
2018-05-21 4:25 ` Ross Zwisler
2018-04-14 14:13 ` [PATCH v11 52/63] dax: dax_insert_mapping_entry always succeeds Matthew Wilcox
2018-05-21 4:33 ` Ross Zwisler
2018-04-14 14:13 ` [PATCH v11 53/63] dax: Rename some functions Matthew Wilcox
2018-05-21 4:42 ` Ross Zwisler
2018-05-21 10:11 ` Matthew Wilcox
2018-05-22 21:39 ` Ross Zwisler
2018-04-14 14:13 ` [PATCH v11 54/63] dax: Hash on XArray instead of mapping Matthew Wilcox
2018-05-21 4:47 ` Ross Zwisler
2018-05-21 10:25 ` Matthew Wilcox
2018-05-22 21:38 ` Ross Zwisler
2018-04-14 14:13 ` [PATCH v11 55/63] dax: Convert dax_insert_pfn_mkwrite to XArray Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 56/63] dax: Convert __dax_invalidate_entry " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 57/63] dax: Convert dax writeback " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 58/63] dax: Convert page fault handlers " Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 59/63] dax: Return fault code from dax_load_hole Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 60/63] page cache: Finish XArray conversion Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 61/63] radix tree: Remove unused functions Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 62/63] radix tree: Remove radix_tree_update_node_t Matthew Wilcox
2018-04-14 14:13 ` [PATCH v11 63/63] radix tree: Remove radix_tree_clear_tags Matthew Wilcox
2018-04-16 16:01 ` [PATCH v11 00/63] Convert page cache to XArray Ross Zwisler
2018-05-31 21:36 ` Ross Zwisler
2018-05-31 21:37 ` Ross Zwisler
2018-05-31 21:46 ` Matthew Wilcox
2018-05-31 21:53 ` Ross Zwisler
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