From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:60697 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755495AbdLORKo (ORCPT ); Fri, 15 Dec 2017 12:10:44 -0500 Date: Fri, 15 Dec 2017 09:10:12 -0800 From: Matthew Wilcox To: Randy Dunlap Cc: Matthew Wilcox , Ross Zwisler , Jens Axboe , Rehas Sachdeva , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Storing errors in the XArray Message-ID: <20171215171012.GA11918@bombadil.infradead.org> References: <20171206004159.3755-1-willy@infradead.org> <20171206004159.3755-9-willy@infradead.org> <66ad068b-1973-ca41-7bbf-8a0634cc488d@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <66ad068b-1973-ca41-7bbf-8a0634cc488d@infradead.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, Dec 11, 2017 at 03:10:22PM -0800, Randy Dunlap wrote: > > +The XArray does not support storing :c:func:`IS_ERR` pointers; some > > +conflict with data values and others conflict with entries the XArray > > +uses for its own purposes. If you need to store special values which > > +cannot be confused with real kernel pointers, the values 4, 8, ... 4092 > > +are available. > > or if I know that they values are errno-range values, I can just shift them > left by 2 to store them and then shift them right by 2 to use them? On further thought, I like this idea so much, it's worth writing helpers for this usage. And test-suite (also doubles as a demonstration of how to use it). diff --git a/include/linux/xarray.h b/include/linux/xarray.h index c616e9319c7c..53aa251df57a 100644 --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -232,6 +232,39 @@ static inline bool xa_is_value(const void *entry) return (unsigned long)entry & 1; } +/** + * xa_mk_errno() - Create an XArray entry from an error number. + * @error: Error number to store in XArray. + * + * Return: An entry suitable for storing in the XArray. + */ +static inline void *xa_mk_errno(long error) +{ + return (void *)(error << 2); +} + +/** + * xa_to_errno() - Get error number stored in an XArray entry. + * @entry: XArray entry. + * + * Return: The error number stored in the XArray entry. + */ +static inline unsigned long xa_to_errno(const void *entry) +{ + return (long)entry >> 2; +} + +/** + * xa_is_errno() - Determine if an entry is an errno. + * @entry: XArray entry. + * + * Return: True if the entry is an errno, false if it is a pointer. + */ +static inline bool xa_is_errno(const void *entry) +{ + return (((unsigned long)entry & 3) == 0) && (entry > (void *)-4096); +} + /** * xa_is_internal() - Is the entry an internal entry? * @entry: Entry retrieved from the XArray diff --git a/tools/testing/radix-tree/xarray-test.c b/tools/testing/radix-tree/xarray-test.c index 43111786ebdd..b843cedf3988 100644 --- a/tools/testing/radix-tree/xarray-test.c +++ b/tools/testing/radix-tree/xarray-test.c @@ -29,7 +29,13 @@ void check_xa_err(struct xarray *xa) assert(xa_err(xa_store(xa, 1, xa_mk_value(0), GFP_KERNEL)) == 0); assert(xa_err(xa_store(xa, 1, NULL, 0)) == 0); // kills the test-suite :-( -// assert(xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) == -EINVAL); +// assert(xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) == -EINVAL); + + assert(xa_err(xa_store(xa, 0, xa_mk_errno(-ENOMEM), GFP_KERNEL)) == 0); + assert(xa_err(xa_load(xa, 0)) == 0); + assert(xa_is_errno(xa_load(xa, 0)) == true); + assert(xa_to_errno(xa_load(xa, 0)) == -ENOMEM); + xa_erase(xa, 0); } void check_xa_tag(struct xarray *xa) From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 15 Dec 2017 09:10:12 -0800 From: Matthew Wilcox To: Randy Dunlap Cc: Matthew Wilcox , Ross Zwisler , Jens Axboe , Rehas Sachdeva , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Storing errors in the XArray Message-ID: <20171215171012.GA11918@bombadil.infradead.org> References: <20171206004159.3755-1-willy@infradead.org> <20171206004159.3755-9-willy@infradead.org> <66ad068b-1973-ca41-7bbf-8a0634cc488d@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <66ad068b-1973-ca41-7bbf-8a0634cc488d@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: On Mon, Dec 11, 2017 at 03:10:22PM -0800, Randy Dunlap wrote: > > +The XArray does not support storing :c:func:`IS_ERR` pointers; some > > +conflict with data values and others conflict with entries the XArray > > +uses for its own purposes. If you need to store special values which > > +cannot be confused with real kernel pointers, the values 4, 8, ... 4092 > > +are available. > > or if I know that they values are errno-range values, I can just shift them > left by 2 to store them and then shift them right by 2 to use them? On further thought, I like this idea so much, it's worth writing helpers for this usage. And test-suite (also doubles as a demonstration of how to use it). diff --git a/include/linux/xarray.h b/include/linux/xarray.h index c616e9319c7c..53aa251df57a 100644 --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -232,6 +232,39 @@ static inline bool xa_is_value(const void *entry) return (unsigned long)entry & 1; } +/** + * xa_mk_errno() - Create an XArray entry from an error number. + * @error: Error number to store in XArray. + * + * Return: An entry suitable for storing in the XArray. + */ +static inline void *xa_mk_errno(long error) +{ + return (void *)(error << 2); +} + +/** + * xa_to_errno() - Get error number stored in an XArray entry. + * @entry: XArray entry. + * + * Return: The error number stored in the XArray entry. + */ +static inline unsigned long xa_to_errno(const void *entry) +{ + return (long)entry >> 2; +} + +/** + * xa_is_errno() - Determine if an entry is an errno. + * @entry: XArray entry. + * + * Return: True if the entry is an errno, false if it is a pointer. + */ +static inline bool xa_is_errno(const void *entry) +{ + return (((unsigned long)entry & 3) == 0) && (entry > (void *)-4096); +} + /** * xa_is_internal() - Is the entry an internal entry? * @entry: Entry retrieved from the XArray diff --git a/tools/testing/radix-tree/xarray-test.c b/tools/testing/radix-tree/xarray-test.c index 43111786ebdd..b843cedf3988 100644 --- a/tools/testing/radix-tree/xarray-test.c +++ b/tools/testing/radix-tree/xarray-test.c @@ -29,7 +29,13 @@ void check_xa_err(struct xarray *xa) assert(xa_err(xa_store(xa, 1, xa_mk_value(0), GFP_KERNEL)) == 0); assert(xa_err(xa_store(xa, 1, NULL, 0)) == 0); // kills the test-suite :-( -// assert(xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) == -EINVAL); +// assert(xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) == -EINVAL); + + assert(xa_err(xa_store(xa, 0, xa_mk_errno(-ENOMEM), GFP_KERNEL)) == 0); + assert(xa_err(xa_load(xa, 0)) == 0); + assert(xa_is_errno(xa_load(xa, 0)) == true); + assert(xa_to_errno(xa_load(xa, 0)) == -ENOMEM); + xa_erase(xa, 0); } void check_xa_tag(struct xarray *xa) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: Storing errors in the XArray From: Matthew Wilcox Message-Id: <20171215171012.GA11918@bombadil.infradead.org> Date: Fri, 15 Dec 2017 09:10:12 -0800 To: Randy Dunlap Cc: Matthew Wilcox , Ross Zwisler , Jens Axboe , Rehas Sachdeva , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org List-ID: T24gTW9uLCBEZWMgMTEsIDIwMTcgYXQgMDM6MTA6MjJQTSAtMDgwMCwgUmFuZHkgRHVubGFwIHdy b3RlOgo+ID4gK1RoZSBYQXJyYXkgZG9lcyBub3Qgc3VwcG9ydCBzdG9yaW5nIDpjOmZ1bmM6YElT X0VSUmAgcG9pbnRlcnM7IHNvbWUKPiA+ICtjb25mbGljdCB3aXRoIGRhdGEgdmFsdWVzIGFuZCBv dGhlcnMgY29uZmxpY3Qgd2l0aCBlbnRyaWVzIHRoZSBYQXJyYXkKPiA+ICt1c2VzIGZvciBpdHMg b3duIHB1cnBvc2VzLiAgSWYgeW91IG5lZWQgdG8gc3RvcmUgc3BlY2lhbCB2YWx1ZXMgd2hpY2gK PiA+ICtjYW5ub3QgYmUgY29uZnVzZWQgd2l0aCByZWFsIGtlcm5lbCBwb2ludGVycywgdGhlIHZh bHVlcyA0LCA4LCAuLi4gNDA5Mgo+ID4gK2FyZSBhdmFpbGFibGUuCj4gCj4gb3IgaWYgSSBrbm93 IHRoYXQgdGhleSB2YWx1ZXMgYXJlIGVycm5vLXJhbmdlIHZhbHVlcywgSSBjYW4ganVzdCBzaGlm dCB0aGVtCj4gbGVmdCBieSAyIHRvIHN0b3JlIHRoZW0gYW5kIHRoZW4gc2hpZnQgdGhlbSByaWdo dCBieSAyIHRvIHVzZSB0aGVtPwoKT24gZnVydGhlciB0aG91Z2h0LCBJIGxpa2UgdGhpcyBpZGVh IHNvIG11Y2gsIGl0J3Mgd29ydGggd3JpdGluZyBoZWxwZXJzCmZvciB0aGlzIHVzYWdlLiAgQW5k IHRlc3Qtc3VpdGUgKGFsc28gZG91YmxlcyBhcyBhIGRlbW9uc3RyYXRpb24gb2YgaG93CnRvIHVz ZSBpdCkuCi0tLQpUbyB1bnN1YnNjcmliZSBmcm9tIHRoaXMgbGlzdDogc2VuZCB0aGUgbGluZSAi dW5zdWJzY3JpYmUgbGludXgtdXNiIiBpbgp0aGUgYm9keSBvZiBhIG1lc3NhZ2UgdG8gbWFqb3Jk b21vQHZnZXIua2VybmVsLm9yZwpNb3JlIG1ham9yZG9tbyBpbmZvIGF0ICBodHRwOi8vdmdlci5r ZXJuZWwub3JnL21ham9yZG9tby1pbmZvLmh0bWwKCmRpZmYgLS1naXQgYS9pbmNsdWRlL2xpbnV4 L3hhcnJheS5oIGIvaW5jbHVkZS9saW51eC94YXJyYXkuaAppbmRleCBjNjE2ZTkzMTljN2MuLjUz YWEyNTFkZjU3YSAxMDA2NDQKLS0tIGEvaW5jbHVkZS9saW51eC94YXJyYXkuaAorKysgYi9pbmNs dWRlL2xpbnV4L3hhcnJheS5oCkBAIC0yMzIsNiArMjMyLDM5IEBAIHN0YXRpYyBpbmxpbmUgYm9v bCB4YV9pc192YWx1ZShjb25zdCB2b2lkICplbnRyeSkKIAlyZXR1cm4gKHVuc2lnbmVkIGxvbmcp ZW50cnkgJiAxOwogfQogCisvKioKKyAqIHhhX21rX2Vycm5vKCkgLSBDcmVhdGUgYW4gWEFycmF5 IGVudHJ5IGZyb20gYW4gZXJyb3IgbnVtYmVyLgorICogQGVycm9yOiBFcnJvciBudW1iZXIgdG8g c3RvcmUgaW4gWEFycmF5LgorICoKKyAqIFJldHVybjogQW4gZW50cnkgc3VpdGFibGUgZm9yIHN0 b3JpbmcgaW4gdGhlIFhBcnJheS4KKyAqLworc3RhdGljIGlubGluZSB2b2lkICp4YV9ta19lcnJu byhsb25nIGVycm9yKQoreworCXJldHVybiAodm9pZCAqKShlcnJvciA8PCAyKTsKK30KKworLyoq CisgKiB4YV90b19lcnJubygpIC0gR2V0IGVycm9yIG51bWJlciBzdG9yZWQgaW4gYW4gWEFycmF5 IGVudHJ5LgorICogQGVudHJ5OiBYQXJyYXkgZW50cnkuCisgKgorICogUmV0dXJuOiBUaGUgZXJy b3IgbnVtYmVyIHN0b3JlZCBpbiB0aGUgWEFycmF5IGVudHJ5LgorICovCitzdGF0aWMgaW5saW5l IHVuc2lnbmVkIGxvbmcgeGFfdG9fZXJybm8oY29uc3Qgdm9pZCAqZW50cnkpCit7CisJcmV0dXJu IChsb25nKWVudHJ5ID4+IDI7Cit9CisKKy8qKgorICogeGFfaXNfZXJybm8oKSAtIERldGVybWlu ZSBpZiBhbiBlbnRyeSBpcyBhbiBlcnJuby4KKyAqIEBlbnRyeTogWEFycmF5IGVudHJ5LgorICoK KyAqIFJldHVybjogVHJ1ZSBpZiB0aGUgZW50cnkgaXMgYW4gZXJybm8sIGZhbHNlIGlmIGl0IGlz IGEgcG9pbnRlci4KKyAqLworc3RhdGljIGlubGluZSBib29sIHhhX2lzX2Vycm5vKGNvbnN0IHZv aWQgKmVudHJ5KQoreworCXJldHVybiAoKCh1bnNpZ25lZCBsb25nKWVudHJ5ICYgMykgPT0gMCkg JiYgKGVudHJ5ID4gKHZvaWQgKiktNDA5Nik7Cit9CisKIC8qKgogICogeGFfaXNfaW50ZXJuYWwo KSAtIElzIHRoZSBlbnRyeSBhbiBpbnRlcm5hbCBlbnRyeT8KICAqIEBlbnRyeTogRW50cnkgcmV0 cmlldmVkIGZyb20gdGhlIFhBcnJheQpkaWZmIC0tZ2l0IGEvdG9vbHMvdGVzdGluZy9yYWRpeC10 cmVlL3hhcnJheS10ZXN0LmMgYi90b29scy90ZXN0aW5nL3JhZGl4LXRyZWUveGFycmF5LXRlc3Qu YwppbmRleCA0MzExMTc4NmViZGQuLmI4NDNjZWRmMzk4OCAxMDA2NDQKLS0tIGEvdG9vbHMvdGVz dGluZy9yYWRpeC10cmVlL3hhcnJheS10ZXN0LmMKKysrIGIvdG9vbHMvdGVzdGluZy9yYWRpeC10 cmVlL3hhcnJheS10ZXN0LmMKQEAgLTI5LDcgKzI5LDEzIEBAIHZvaWQgY2hlY2tfeGFfZXJyKHN0 cnVjdCB4YXJyYXkgKnhhKQogCWFzc2VydCh4YV9lcnIoeGFfc3RvcmUoeGEsIDEsIHhhX21rX3Zh bHVlKDApLCBHRlBfS0VSTkVMKSkgPT0gMCk7CiAJYXNzZXJ0KHhhX2Vycih4YV9zdG9yZSh4YSwg MSwgTlVMTCwgMCkpID09IDApOwogLy8ga2lsbHMgdGhlIHRlc3Qtc3VpdGUgOi0oCi0vLyAgICAg YXNzZXJ0KHhhX2Vycih4YV9zdG9yZSh4YSwgMCwgeGFfbWtfaW50ZXJuYWwoMCksIDApKSA9PSAt RUlOVkFMKTsKKy8vCWFzc2VydCh4YV9lcnIoeGFfc3RvcmUoeGEsIDAsIHhhX21rX2ludGVybmFs KDApLCAwKSkgPT0gLUVJTlZBTCk7CisKKwlhc3NlcnQoeGFfZXJyKHhhX3N0b3JlKHhhLCAwLCB4 YV9ta19lcnJubygtRU5PTUVNKSwgR0ZQX0tFUk5FTCkpID09IDApOworCWFzc2VydCh4YV9lcnIo eGFfbG9hZCh4YSwgMCkpID09IDApOworCWFzc2VydCh4YV9pc19lcnJubyh4YV9sb2FkKHhhLCAw KSkgPT0gdHJ1ZSk7CisJYXNzZXJ0KHhhX3RvX2Vycm5vKHhhX2xvYWQoeGEsIDApKSA9PSAtRU5P TUVNKTsKKwl4YV9lcmFzZSh4YSwgMCk7CiB9CiAKIHZvaWQgY2hlY2tfeGFfdGFnKHN0cnVjdCB4 YXJyYXkgKnhhKQo=