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2024-03-12auxdisplay: hd44780: Convert to platform remove callback returning voidUwe Kleine-König1-3/+2
The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-03-12auxdisplay: cfag12864bfb: Convert to platform remove callback returning voidUwe Kleine-König1-4/+2
The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-03-11auxdisplay: seg-led-gpio: Import linedisp namespaceChris Packham1-0/+1
The seg-led-gpio driver uses symbols from the linedisp namespace. Ensure these are imported. Fixes: 899383f9ecf5 ("auxdisplay: Add 7-segment LED display driver") Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Closes: https://lore.kernel.org/r/202403100401.IDre04gu-lkp@intel.com/ Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-03-08dt-bindings: auxdisplay: Add bindings for generic 7-segment LEDChris Packham1-0/+55
Add bindings for a generic 7-segment LED display using GPIOs. Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-03-08auxdisplay: Add 7-segment LED display driverChris Packham3-0/+124
Add a driver for a 7-segment LED display. At the moment only one character is supported but it should be possible to expand this to support more characters and/or 14-segment displays in the future. Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26auxdisplay: Add driver for MAX695x 7-segment LED controllersAndy Shevchenko3-0/+209
Add initial driver for the MAX6958 and MAX6959 7-segment LED controllers. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26dt-bindings: auxdisplay: Add Maxim MAX6958/6959Andy Shevchenko1-0/+44
Add initial device tree documentation for Maxim MAX6958/6959. As per reviewer's request mention the fact of absence the reset and power enable pins, since the hardware is quite simple. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
2024-02-26auxdisplay: ht16k33: Drop struct ht16k33_segAndy Shevchenko1-15/+9
The struct ht16k33_seg is repeating struct linedisp. Use the latter directly. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26auxdisplay: ht16k33: Switch to use line display character mappingAndy Shevchenko1-73/+30
Since line display library supports necessary bits to map the characters (if required), switch this driver to use that. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Robin van der Gracht <robin@protonic.nl> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26auxdisplay: ht16k33: Define a few helper macrosAndy Shevchenko1-12/+16
Define a few helper macros — wrappers on container_of() — for easier maintenance in the future. While at it, include missing container_of.h. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26auxdisplay: ht16k33: Move ht16k33_linedisp_ops downAndy Shevchenko1-12/+12
We will need the update functions to be defined before ht16k33_linedisp_ops. Move the latter down in the code. No functional change intended. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Robin van der Gracht <robin@protonic.nl> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26auxdisplay: ht16k33: Add default to switch-casesAndy Shevchenko1-5/+9
Currently the compiler (GCC) is able to figure out that there is no other choices possible than those that are already listed in the switch-cases. However, if we want to move some code to the callback, compiler will start complaining that no default is defined. Make sure we have all switch-cases equiped with default. Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-26auxdisplay: linedisp: Allocate buffer for the stringAndy Shevchenko4-21/+18
Always allocate a buffer for the currently displayed characters. It makes the line display API simpler. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Add support for overriding character mappingAndy Shevchenko2-2/+140
There is already the driver using character mapping table for 7 or 14 segment display. It is possible to override it. Make the similar in the line display library to allow other drivers to utilise the same functionality. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Provide struct linedisp_ops for future extensionAndy Shevchenko4-15/+35
Currently the line display library doesn't scale in case we want to provide more operations. Prepare the library to take a newly created struct linedisp_ops that scales. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Move exported symbols to a namespaceAndy Shevchenko3-2/+4
Avoid unnecessary pollution of the global symbol namespace by moving library functions in to a specific namespace and import that into the drivers that make use of the functions. For more info: https://lwn.net/Articles/760045/ Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Add missing header(s)Andy Shevchenko2-0/+6
Do not imply that some of the generic headers may be always included. Instead, include explicitly what we are direct user of. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Unshadow error codes in ->store()Andy Shevchenko1-2/+5
kstrtox() may return different error codes. Unshadow them in the ->store() callback to give better error report. While at it, add missing kstrtox.h inclusion. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Use unique number for idAndy Shevchenko2-3/+12
The absence of decrementation of linedisp_id is incorrect in two ways, i.e. it may cause: - an ID exhaustion - (and if the above is addressed) a duplicate id number may be allocated next time a device is added Replace above mentioned approach by using IDA framework. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: linedisp: Free allocated resources in ->release()Andy Shevchenko1-1/+8
While there is no issue currently with the resources allocation, the code may still be made more robust by deallocating message in the ->release() callback. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: img-ascii-lcd: Make container_of() no-op for struct linedispAndy Shevchenko1-2/+2
Move embedded struct linedisp member to make container_of() no-op. Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-15auxdisplay: panel: Switch to use module_parport_driver()Andy Shevchenko1-113/+89
Switch to use module_parport_driver() to reduce boilerplate code. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-14dt-bindings: auxdisplay: hit,hd44780: use defines for GPIO flagsKrzysztof Kozlowski1-8/+8
Improve example DTS readability by using known defines for GPIO flags. Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-14dt-bindings: auxdisplay: adjust example indentation and use generic node namesKrzysztof Kozlowski4-64/+66
The example DTS should be indented with two or four (preferred) spaces, as mentioned in Writing Schema document. While re-indenting, change the node names to somehow generic names, as expected by Devicetree specification. Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ralf Schlatterbeck <rsc@runtux.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-14auxdisplay: Add 7 and 14 segment mappings to MAINTAINERSAndy Shevchenko1-0/+2
The mapping files are tightly related to auxdisplay subsystem. Add them to the MAINTAINERS database. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
2024-02-12auxdisplay: Take over maintainership, but in Odd Fixes modeAndy Shevchenko1-2/+4
I have no time for this, but since it looks like I'm the main contributor for the last few years to the subsystem, I'll take it for now. Geert agreed to help me as a designated reviewer. Let's see how it will go... Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-01-22Linux 6.8-rc1Linus Torvalds1-2/+2
2024-01-22Merge tag 'bcachefs-2024-01-21' of https://evilpiepirate.org/git/bcachefsLinus Torvalds78-1426/+1629
Pull more bcachefs updates from Kent Overstreet: "Some fixes, Some refactoring, some minor features: - Assorted prep work for disk space accounting rewrite - BTREE_TRIGGER_ATOMIC: after combining our trigger callbacks, this makes our trigger context more explicit - A few fixes to avoid excessive transaction restarts on multithreaded workloads: fstests (in addition to ktest tests) are now checking slowpath counters, and that's shaking out a few bugs - Assorted tracepoint improvements - Starting to break up bcachefs_format.h and move on disk types so they're with the code they belong to; this will make room to start documenting the on disk format better. - A few minor fixes" * tag 'bcachefs-2024-01-21' of https://evilpiepirate.org/git/bcachefs: (46 commits) bcachefs: Improve inode_to_text() bcachefs: logged_ops_format.h bcachefs: reflink_format.h bcachefs; extents_format.h bcachefs: ec_format.h bcachefs: subvolume_format.h bcachefs: snapshot_format.h bcachefs: alloc_background_format.h bcachefs: xattr_format.h bcachefs: dirent_format.h bcachefs: inode_format.h bcachefs; quota_format.h bcachefs: sb-counters_format.h bcachefs: counters.c -> sb-counters.c bcachefs: comment bch_subvolume bcachefs: bch_snapshot::btime bcachefs: add missing __GFP_NOWARN bcachefs: opts->compression can now also be applied in the background bcachefs: Prep work for variable size btree node buffers bcachefs: grab s_umount only if snapshotting ...
2024-01-21Merge tag 'timers-core-2024-01-21' of ↵Linus Torvalds7-12/+41
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer updates from Thomas Gleixner: "Updates for time and clocksources: - A fix for the idle and iowait time accounting vs CPU hotplug. The time is reset on CPU hotplug which makes the accumulated systemwide time jump backwards. - Assorted fixes and improvements for clocksource/event drivers" * tag 'timers-core-2024-01-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug clocksource/drivers/ep93xx: Fix error handling during probe clocksource/drivers/cadence-ttc: Fix some kernel-doc warnings clocksource/drivers/timer-ti-dm: Fix make W=n kerneldoc warnings clocksource/timer-riscv: Add riscv_clock_shutdown callback dt-bindings: timer: Add StarFive JH8100 clint dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs
2024-01-21Merge tag 'powerpc-6.8-2' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc fixes from Aneesh Kumar: - Increase default stack size to 32KB for Book3S Thanks to Michael Ellerman. * tag 'powerpc-6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/64s: Increase default stack size to 32KB
2024-01-21bcachefs: Improve inode_to_text()Kent Overstreet1-7/+18
Add line breaks - inode_to_text() is now much easier to read. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: logged_ops_format.hKent Overstreet2-27/+31
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: reflink_format.hKent Overstreet3-47/+48
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs; extents_format.hKent Overstreet2-279/+284
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: ec_format.hKent Overstreet2-16/+20
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: subvolume_format.hKent Overstreet2-32/+36
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: snapshot_format.hKent Overstreet2-33/+37
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: alloc_background_format.hKent Overstreet2-93/+94
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: xattr_format.hKent Overstreet2-15/+20
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: dirent_format.hKent Overstreet2-39/+43
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: inode_format.hKent Overstreet2-164/+167
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs; quota_format.hKent Overstreet2-42/+48
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: sb-counters_format.hKent Overstreet2-95/+100
bcachefs_format.h has gotten too big; let's do some organizing. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: counters.c -> sb-counters.cKent Overstreet5-8/+7
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: comment bch_subvolumeKent Overstreet1-0/+3
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: bch_snapshot::btimeKent Overstreet2-0/+3
Add a field to bch_snapshot for creation time; this will be important when we start exposing the snapshot tree to userspace. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: add missing __GFP_NOWARNKent Overstreet1-1/+1
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: opts->compression can now also be applied in the backgroundKent Overstreet11-23/+24
The "apply this compression method in the background" paths now use the compression option if background_compression is not set; this means that setting or changing the compression option will cause existing data to be compressed accordingly in the background. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: Prep work for variable size btree node buffersKent Overstreet18-97/+87
bcachefs btree nodes are big - typically 256k - and btree roots are pinned in memory. As we're now up to 18 btrees, we now have significant memory overhead in mostly empty btree roots. And in the future we're going to start enforcing that certain btree node boundaries exist, to solve lock contention issues - analagous to XFS's AGIs. Thus, we need to start allocating smaller btree node buffers when we can. This patch changes code that refers to the filesystem constant c->opts.btree_node_size to refer to the btree node buffer size - btree_buf_bytes() - where appropriate. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-01-21bcachefs: grab s_umount only if snapshottingSu Yue1-6/+5
When I was testing mongodb over bcachefs with compression, there is a lockdep warning when snapshotting mongodb data volume. $ cat test.sh prog=bcachefs $prog subvolume create /mnt/data $prog subvolume create /mnt/data/snapshots while true;do $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s) sleep 1s done $ cat /etc/mongodb.conf systemLog: destination: file logAppend: true path: /mnt/data/mongod.log storage: dbPath: /mnt/data/ lockdep reports: [ 3437.452330] ====================================================== [ 3437.452750] WARNING: possible circular locking dependency detected [ 3437.453168] 6.7.0-rc7-custom+ #85 Tainted: G E [ 3437.453562] ------------------------------------------------------ [ 3437.453981] bcachefs/35533 is trying to acquire lock: [ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190 [ 3437.454875] but task is already holding lock: [ 3437.455268] ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.456009] which lock already depends on the new lock. [ 3437.456553] the existing dependency chain (in reverse order) is: [ 3437.457054] -> #3 (&type->s_umount_key#48){.+.+}-{3:3}: [ 3437.457507] down_read+0x3e/0x170 [ 3437.457772] bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.458206] __x64_sys_ioctl+0x93/0xd0 [ 3437.458498] do_syscall_64+0x42/0xf0 [ 3437.458779] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.459155] -> #2 (&c->snapshot_create_lock){++++}-{3:3}: [ 3437.459615] down_read+0x3e/0x170 [ 3437.459878] bch2_truncate+0x82/0x110 [bcachefs] [ 3437.460276] bchfs_truncate+0x254/0x3c0 [bcachefs] [ 3437.460686] notify_change+0x1f1/0x4a0 [ 3437.461283] do_truncate+0x7f/0xd0 [ 3437.461555] path_openat+0xa57/0xce0 [ 3437.461836] do_filp_open+0xb4/0x160 [ 3437.462116] do_sys_openat2+0x91/0xc0 [ 3437.462402] __x64_sys_openat+0x53/0xa0 [ 3437.462701] do_syscall_64+0x42/0xf0 [ 3437.462982] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.463359] -> #1 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}: [ 3437.463843] down_write+0x3b/0xc0 [ 3437.464223] bch2_write_iter+0x5b/0xcc0 [bcachefs] [ 3437.464493] vfs_write+0x21b/0x4c0 [ 3437.464653] ksys_write+0x69/0xf0 [ 3437.464839] do_syscall_64+0x42/0xf0 [ 3437.465009] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.465231] -> #0 (sb_writers#10){.+.+}-{0:0}: [ 3437.465471] __lock_acquire+0x1455/0x21b0 [ 3437.465656] lock_acquire+0xc6/0x2b0 [ 3437.465822] mnt_want_write+0x46/0x1a0 [ 3437.465996] filename_create+0x62/0x190 [ 3437.466175] user_path_create+0x2d/0x50 [ 3437.466352] bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs] [ 3437.466617] __x64_sys_ioctl+0x93/0xd0 [ 3437.466791] do_syscall_64+0x42/0xf0 [ 3437.466957] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.467180] other info that might help us debug this: [ 3437.469670] 2 locks held by bcachefs/35533: other info that might help us debug this: [ 3437.467507] Chain exists of: sb_writers#10 --> &c->snapshot_create_lock --> &type->s_umount_key#48 [ 3437.467979] Possible unsafe locking scenario: [ 3437.468223] CPU0 CPU1 [ 3437.468405] ---- ---- [ 3437.468585] rlock(&type->s_umount_key#48); [ 3437.468758] lock(&c->snapshot_create_lock); [ 3437.469030] lock(&type->s_umount_key#48); [ 3437.469291] rlock(sb_writers#10); [ 3437.469434] *** DEADLOCK *** [ 3437.469670] 2 locks held by bcachefs/35533: [ 3437.469838] #0: ffffa0a02ce00a88 (&c->snapshot_create_lock){++++}-{3:3}, at: bch2_fs_file_ioctl+0x1e3/0xc90 [bcachefs] [ 3437.470294] #1: ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.470744] stack backtrace: [ 3437.470922] CPU: 7 PID: 35533 Comm: bcachefs Kdump: loaded Tainted: G E 6.7.0-rc7-custom+ #85 [ 3437.471313] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 [ 3437.471694] Call Trace: [ 3437.471795] <TASK> [ 3437.471884] dump_stack_lvl+0x57/0x90 [ 3437.472035] check_noncircular+0x132/0x150 [ 3437.472202] __lock_acquire+0x1455/0x21b0 [ 3437.472369] lock_acquire+0xc6/0x2b0 [ 3437.472518] ? filename_create+0x62/0x190 [ 3437.472683] ? lock_is_held_type+0x97/0x110 [ 3437.472856] mnt_want_write+0x46/0x1a0 [ 3437.473025] ? filename_create+0x62/0x190 [ 3437.473204] filename_create+0x62/0x190 [ 3437.473380] user_path_create+0x2d/0x50 [ 3437.473555] bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs] [ 3437.473819] ? lock_acquire+0xc6/0x2b0 [ 3437.474002] ? __fget_files+0x2a/0x190 [ 3437.474195] ? __fget_files+0xbc/0x190 [ 3437.474380] ? lock_release+0xc5/0x270 [ 3437.474567] ? __x64_sys_ioctl+0x93/0xd0 [ 3437.474764] ? __pfx_bch2_fs_file_ioctl+0x10/0x10 [bcachefs] [ 3437.475090] __x64_sys_ioctl+0x93/0xd0 [ 3437.475277] do_syscall_64+0x42/0xf0 [ 3437.475454] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.475691] RIP: 0033:0x7f2743c313af ====================================================== In __bch2_ioctl_subvolume_create(), we grab s_umount unconditionally and unlock it at the end of the function. There is a comment "why do we need this lock?" about the lock coming from commit 42d237320e98 ("bcachefs: Snapshot creation, deletion") The reason is that __bch2_ioctl_subvolume_create() calls sync_inodes_sb() which enforce locked s_umount to writeback all dirty nodes before doing snapshot works. Fix it by read locking s_umount for snapshotting only and unlocking s_umount after sync_inodes_sb(). Signed-off-by: Su Yue <glass.su@suse.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>