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Violators will be prosecuted for from ; Fri, 19 Jul 2019 09:47:48 +0100 Subject: Re: [PATCH AUTOSEL 5.2 149/171] s390/dasd: Make layout analysis ESE compatible References: <20190719035643.14300-1-sashal@kernel.org> <20190719035643.14300-149-sashal@kernel.org> From: =?UTF-8?Q?Jan_H=c3=b6ppner?= Date: Fri, 19 Jul 2019 10:47:42 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit Message-Id: <018f17c4-07c9-7fcf-1f22-0a712b452b25@linux.ibm.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Christian Borntraeger , Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Stefan Haberland , Vasily Gorbik , linux-s390@vger.kernel.org, Heiko Carstens On 19.07.19 09:47, Christian Borntraeger wrote: > The comment is true for all stable versions. > > This patch is part of a larger series that enables ESE volumes. > I think it should not go alone as other patches like > 5e2b17e712cf s390/dasd: Add dynamic formatting support for ESE volumes > are needed to actually work with ESE volumes. > So I suggest to drop this patch. > Jan, Stefan, do you agree? > This patch is a requirement for ESE volumes to work and doesn't add any value alone. I suggest to drop this patch as well. Jan > > > On 19.07.19 05:56, Sasha Levin wrote: >> From: Jan Höppner >> >> [ Upstream commit ce6915f5343f5f2a2a937b683d8ffbf12dab3ad4 ] >> >> The disk layout and volume information of a DASD reside in the first two >> tracks of cylinder 0. When a DASD is set online, currently the first >> three tracks are read and analysed to confirm an expected layout. >> >> For CDL (Compatible Disk Layout) only count area data of the first track >> is evaluated and checked against expected key and data lengths. For LDL >> (Linux Disk Layout) the first and third track is evaluated. However, >> an LDL formatted volume is expected to be in the same format across all >> tracks. Checking the third track therefore doesn't have any more value >> than checking any other track at random. >> >> Now, an Extent Space Efficient (ESE) DASD is initialised by only >> formatting the first two tracks, as those tracks always contain all >> information necessarry. >> >> Checking the third track on an ESE volume will therefore most likely >> fail with a record not found error, as the third track will be empty. >> This in turn leads to the device being recognised with a volume size of >> 0. Attempts to write volume information on the first two tracks then >> fail with "no space left on device" errors. >> >> Initialising the first three tracks for an ESE volume is not a viable >> solution, because the third track is already a regular track and could >> contain user data. With that there is potential for data corruption. >> >> Instead, always only analyse the first two tracks, as it is sufficiant >> for both CDL and LDL, and allow ESE volumes to be recognised as well. >> >> Signed-off-by: Jan Höppner >> Reviewed-by: Stefan Haberland >> Signed-off-by: Vasily Gorbik >> Signed-off-by: Sasha Levin >> --- >> drivers/s390/block/dasd_eckd.c | 12 ++++++------ >> 1 file changed, 6 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c >> index c09039eea707..c7aec1b44b7c 100644 >> --- a/drivers/s390/block/dasd_eckd.c >> +++ b/drivers/s390/block/dasd_eckd.c >> @@ -157,7 +157,7 @@ static const int sizes_trk0[] = { 28, 148, 84 }; >> #define LABEL_SIZE 140 >> >> /* head and record addresses of count_area read in analysis ccw */ >> -static const int count_area_head[] = { 0, 0, 0, 0, 2 }; >> +static const int count_area_head[] = { 0, 0, 0, 0, 1 }; >> static const int count_area_rec[] = { 1, 2, 3, 4, 1 }; >> >> static inline unsigned int >> @@ -1823,8 +1823,8 @@ dasd_eckd_analysis_ccw(struct dasd_device *device) >> if (IS_ERR(cqr)) >> return cqr; >> ccw = cqr->cpaddr; >> - /* Define extent for the first 3 tracks. */ >> - define_extent(ccw++, cqr->data, 0, 2, >> + /* Define extent for the first 2 tracks. */ >> + define_extent(ccw++, cqr->data, 0, 1, >> DASD_ECKD_CCW_READ_COUNT, device, 0); >> LO_data = cqr->data + sizeof(struct DE_eckd_data); >> /* Locate record for the first 4 records on track 0. */ >> @@ -1843,9 +1843,9 @@ dasd_eckd_analysis_ccw(struct dasd_device *device) >> count_data++; >> } >> >> - /* Locate record for the first record on track 2. */ >> + /* Locate record for the first record on track 1. */ >> ccw[-1].flags |= CCW_FLAG_CC; >> - locate_record(ccw++, LO_data++, 2, 0, 1, >> + locate_record(ccw++, LO_data++, 1, 0, 1, >> DASD_ECKD_CCW_READ_COUNT, device, 0); >> /* Read count ccw. */ >> ccw[-1].flags |= CCW_FLAG_CC; >> @@ -1967,7 +1967,7 @@ static int dasd_eckd_end_analysis(struct dasd_block *block) >> } >> } >> if (i == 3) >> - count_area = &private->count_area[4]; >> + count_area = &private->count_area[3]; >> >> if (private->uses_cdl == 0) { >> for (i = 0; i < 5; i++) { >>