kernel/linux.git/drivers/md/raid0.h, branch v6.6.132

md/raid0: add discard support for the 'original' layout

2023-06-30T22:43:50+00:00

We've found that using raid0 with the 'original' layout and discard enabled with different disk sizes (such that at least two zones are created) can result in data corruption. This is due to the fact that the discard handling in 'raid0_handle_discard()' assumes the 'alternate' layout. We've seen this corruption using ext4 but other filesystems are likely susceptible as well. More specifically, while multiple zones are necessary to create the corruption, the corruption may not occur with multiple zones if they layout in such a way the layout matches what the 'alternate' layout would have produced. Thus, not all raid0 devices with the 'original' layout, different size disks and discard enabled will encounter this corruption. The 3.14 kernel inadvertently changed the raid0 disk layout for different size disks. Thus, running a pre-3.14 kernel and post-3.14 kernel on the same raid0 array could corrupt data. This lead to the creation of the 'original' layout (to match the pre-3.14 layout) and the 'alternate' layout (to match the post 3.14 layout) in the 5.4 kernel time frame and an option to tell the kernel which layout to use (since it couldn't be autodetected). However, when the 'original' layout was added back to 5.4 discard support for the 'original' layout was not added leading this issue. I've been able to reliably reproduce the corruption with the following test case: 1. create raid0 array with different size disks using original layout 2. mkfs 3. mount -o discard 4. create lots of files 5. remove 1/2 the files 6. fstrim -a (or just the mount point for the raid0 array) 7. umount 8. fsck -fn /dev/md0 (spews all sorts of corruptions) Let's fix this by adding proper discard support to the 'original' layout. The fix 'maps' the 'original' layout disks to the order in which they are read/written such that we can compare the disks in the same way that the current 'alternate' layout does. A 'disk_shift' field is added to 'struct strip_zone'. This could be computed on the fly in raid0_handle_discard() but by adding this field, we save some computation in the discard path. Note we could also potentially fix this by re-ordering the disks in the zones that follow the first one, and then always read/writing them using the 'alternate' layout. However, that is seen as a more substantial change, and we are attempting the least invasive fix at this time to remedy the corruption. I've verified the change using the reproducer mentioned above. Typically, the corruption is seen after less than 3 iterations, while the patch has run 500+ iterations. Cc: NeilBrown Cc: Song Liu Fixes: c84a1372df92 ("md/raid0: avoid RAID0 data corruption due to layout confusion.") Cc: stable@vger.kernel.org Signed-off-by: Jason Baron Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230623180523.1901230-1-jbaron@akamai.com

md/raid0: avoid RAID0 data corruption due to layout confusion.

2019-09-13T20:10:05+00:00

If the drives in a RAID0 are not all the same size, the array is divided into zones. The first zone covers all drives, to the size of the smallest. The second zone covers all drives larger than the smallest, up to the size of the second smallest - etc. A change in Linux 3.14 unintentionally changed the layout for the second and subsequent zones. All the correct data is still stored, but each chunk may be assigned to a different device than in pre-3.14 kernels. This can lead to data corruption. It is not possible to determine what layout to use - it depends which kernel the data was written by. So we add a module parameter to allow the old (0) or new (1) layout to be specified, and refused to assemble an affected array if that parameter is not set. Fixes: 20d0189b1012 ("block: Introduce new bio_split()") cc: stable@vger.kernel.org (3.14+) Acked-by: Guoqing Jiang Signed-off-by: NeilBrown Signed-off-by: Song Liu

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55+00:00

Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart Reviewed-by: Philippe Ombredanne Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

block: kill merge_bvec_fn() completely

2015-08-13T18:31:57+00:00

As generic_make_request() is now able to handle arbitrarily sized bios, it's no longer necessary for each individual block driver to define its own ->merge_bvec_fn() callback. Remove every invocation completely. Cc: Jens Axboe Cc: Lars Ellenberg Cc: drbd-user@lists.linbit.com Cc: Jiri Kosina Cc: Yehuda Sadeh Cc: Sage Weil Cc: Alex Elder Cc: ceph-devel@vger.kernel.org Cc: Alasdair Kergon Cc: Mike Snitzer Cc: dm-devel@redhat.com Cc: Neil Brown Cc: linux-raid@vger.kernel.org Cc: Christoph Hellwig Cc: "Martin K. Petersen" Acked-by: NeilBrown (for the 'md' bits) Acked-by: Mike Snitzer Signed-off-by: Kent Overstreet [dpark: also remove ->merge_bvec_fn() in dm-thin as well as dm-era-target, and resolve merge conflicts] Signed-off-by: Dongsu Park Signed-off-by: Ming Lin Signed-off-by: Jens Axboe

md: add proper merge_bvec handling to RAID0 and Linear.

2012-03-19T01:46:39+00:00

These personalities currently set a max request size of one page when any member device has a merge_bvec_fn because they don't bother to call that function. This causes extra works in splitting and combining requests. So make the extra effort to call the merge_bvec_fn when it exists so that we end up with larger requests out the bottom. Signed-off-by: NeilBrown

md/raid0: typedef removal: raid0_conf_t -> struct r0conf

2011-10-11T05:48:59+00:00

Signed-off-by: NeilBrown

md: removing typedefs: mdk_rdev_t -> struct md_rdev

2011-10-11T05:45:26+00:00

The typedefs are just annoying. 'mdk' probably refers to 'md_k.h' which used to be an include file that defined this thing. Signed-off-by: NeilBrown

md: fix handling of array level takeover that re-arranges devices.

2010-06-24T03:33:24+00:00

Most array level changes leave the list of devices largely unchanged, possibly causing one at the end to become redundant. However conversions between RAID0 and RAID10 need to renumber all devices (except 0). This renumbering is currently being done in the ->run method when the new personality takes over. However this is too late as the common code in md.c might already have invalidated some of the devices if they had a ->raid_disk number that appeared to high. Moving it into the ->takeover method is too early as the array is still active at that time and wrong ->raid_disk numbers could cause confusion. So add a ->new_raid_disk field to mdk_rdev_s and use it to communicate the new raid_disk number. Now the common code knows exactly which devices need to be renumbered, and which can be invalidated, and can do it all at a convenient time when the array is suspend. It can also update some symlinks in sysfs which previously were not be updated correctly. Reported-by: Maciej Trela Signed-off-by: NeilBrown

md: Add support for Raid5->Raid0 and Raid10->Raid0 takeover

2010-05-18T05:27:48+00:00

Signed-off-by: Maciej Trela Signed-off-by: NeilBrown

md: remove mddev_to_conf "helper" macro

2009-06-16T06:54:21+00:00

Having a macro just to cast a void* isn't really helpful. I would must rather see that we are simply de-referencing ->private, than have to know what the macro does. So open code the macro everywhere and remove the pointless cast. Signed-off-by: NeilBrown