From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Matthew Wilcox To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Matthew Wilcox , Jan Kara , Jeff Layton , Lukas Czerner , Ross Zwisler , Christoph Hellwig , Goldwyn Rodrigues , Nicholas Piggin , Ryusuke Konishi , linux-nilfs@vger.kernel.org, Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net Subject: [PATCH v13 13/72] xarray: Add xa_extract Date: Mon, 11 Jun 2018 07:05:40 -0700 Message-Id: <20180611140639.17215-14-willy@infradead.org> In-Reply-To: <20180611140639.17215-1-willy@infradead.org> References: <20180611140639.17215-1-willy@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: From: Matthew Wilcox This function combines the functionality of radix_tree_gang_lookup() and radix_tree_gang_lookup_tagged(). It extracts entries matching the specified filter into a normal array. Signed-off-by: Matthew Wilcox --- include/linux/xarray.h | 2 ++ lib/xarray.c | 80 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 82 insertions(+) diff --git a/include/linux/xarray.h b/include/linux/xarray.h index 89f37d841d18..3764f4b4c1a8 100644 --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -227,6 +227,8 @@ void *xa_find(struct xarray *xa, unsigned long *index, unsigned long max, xa_tag_t) __attribute__((nonnull(2))); void *xa_find_after(struct xarray *xa, unsigned long *index, unsigned long max, xa_tag_t) __attribute__((nonnull(2))); +unsigned int xa_extract(struct xarray *, void **dst, unsigned long start, + unsigned long max, unsigned int n, xa_tag_t); /** * xa_init() - Initialise an empty XArray. diff --git a/lib/xarray.c b/lib/xarray.c index c6b7adcd6131..c3a53f09aa88 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1427,6 +1427,86 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp, } EXPORT_SYMBOL(xa_find_after); +static unsigned int xas_extract_present(struct xa_state *xas, void **dst, + unsigned long max, unsigned int n) +{ + void *entry; + unsigned int i = 0; + + rcu_read_lock(); + xas_for_each(xas, entry, max) { + if (xas_retry(xas, entry)) + continue; + dst[i++] = entry; + if (i == n) + break; + } + rcu_read_unlock(); + + return i; +} + +static unsigned int xas_extract_tag(struct xa_state *xas, void **dst, + unsigned long max, unsigned int n, xa_tag_t tag) +{ + void *entry; + unsigned int i = 0; + + rcu_read_lock(); + xas_for_each_tagged(xas, entry, max, tag) { + if (xas_retry(xas, entry)) + continue; + dst[i++] = entry; + if (i == n) + break; + } + rcu_read_unlock(); + + return i; +} + +/** + * xa_extract() - Copy selected entries from the XArray into a normal array. + * @xa: The source XArray to copy from. + * @dst: The buffer to copy entries into. + * @start: The first index in the XArray eligible to be selected. + * @max: The last index in the XArray eligible to be selected. + * @n: The maximum number of entries to copy. + * @filter: Selection criterion. + * + * Copies up to @n entries that match @filter from the XArray. The + * copied entries will have indices between @start and @max, inclusive. + * + * The @filter may be an XArray tag value, in which case entries which are + * tagged with that tag will be copied. It may also be %XA_PRESENT, in + * which case non-NULL entries will be copied. + * + * The entries returned may not represent a snapshot of the XArray at a + * moment in time. For example, if another thread stores to index 5, then + * index 10, calling xa_extract() may return the old contents of index 5 + * and the new contents of index 10. Indices not modified while this + * function is running will not be skipped. + * + * If you need stronger guarantees, holding the xa_lock across calls to this + * function will prevent concurrent modification. + * + * Context: Any context. Takes and releases the RCU lock. + * Return: The number of entries copied. + */ +unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start, + unsigned long max, unsigned int n, xa_tag_t filter) +{ + XA_STATE(xas, xa, start); + + if (!n) + return 0; + + if ((__force unsigned int)filter < XA_MAX_TAGS) + return xas_extract_tag(&xas, dst, max, n, filter); + return xas_extract_present(&xas, dst, max, n); +} +EXPORT_SYMBOL(xa_extract); + #ifdef XA_DEBUG void xa_dump_node(const struct xa_node *node) { -- 2.17.1