zpool: add zpool_has_pool() (3f0e1312) · Commits · 戴 / test

This series makes creation of the zpool and compressor dynamic, so that they can be changed at runtime. This makes using/configuring zswap easier, as before this zswap had to be configured at boot time, using boot params. This uses a single list to track both the zpool and compressor together, although Seth had mentioned an alternative which is to track the zpools and compressors using separate lists. In the most common case, only a single zpool and single compressor, using one list is slightly simpler than using two lists, and for the uncommon case of multiple zpools and/or compressors, using one list is slightly less simple (and uses slightly more memory, probably) than using two lists. This patch (of 4): Add zpool_has_pool() function, indicating if the specified type of zpool is available (i.e. zsmalloc or zbud). This allows checking if a pool is available, without actually trying to allocate it, similar to crypto_has_alg(). This is used by a following patch to zswap that enables the dynamic runtime creation of zswap zpools. Signed-off-by:

Dan Streetman <ddstreet@ieee.org> Acked-by:

Seth Jennings <sjennings@variantweb.net> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/zpool.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -36,6 +36,8 @@ enum zpool_mapmode {
		ZPOOL_MM_DEFAULT = ZPOOL_MM_RW
		};

		bool zpool_has_pool(char *type);

		struct zpool zpool_create_pool(char type, char *name,
		gfp_t gfp, const struct zpool_ops *ops);

mm/zpool.c

+33 −0

Original line number	Diff line number	Diff line
		@@ -99,6 +99,39 @@ static void zpool_put_driver(struct zpool_driver *driver)
		module_put(driver->owner);
		}

		/**
		* zpool_has_pool() - Check if the pool driver is available
		* @type The type of the zpool to check (e.g. zbud, zsmalloc)
		*
		* This checks if the @type pool driver is available. This will try to load
		* the requested module, if needed, but there is no guarantee the module will
		* still be loaded and available immediately after calling. If this returns
		* true, the caller should assume the pool is available, but must be prepared
		* to handle the @zpool_create_pool() returning failure. However if this
		* returns false, the caller should assume the requested pool type is not
		* available; either the requested pool type module does not exist, or could
		* not be loaded, and calling @zpool_create_pool() with the pool type will
		* fail.
		*
		* Returns: true if @type pool is available, false if not
		*/
		bool zpool_has_pool(char *type)
		{
		struct zpool_driver *driver = zpool_get_driver(type);

		if (!driver) {
		request_module("zpool-%s", type);
		driver = zpool_get_driver(type);
		}

		if (!driver)
		return false;

		zpool_put_driver(driver);
		return true;
		}
		EXPORT_SYMBOL(zpool_has_pool);

		/**
		* zpool_create_pool() - Create a new zpool
		* @type The type of the zpool to create (e.g. zbud, zsmalloc)

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