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2026-08-07spi: cadence: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use __maybe_unused. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://patch.msgid.link/20260803142003.12857-9-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: bcmbca-hsspi: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use #ifdef guards. This has the advantage of always compiling these functions in, independently of any Kconfig option. Thanks to that, bugs and other regressions are subsequently easier to catch. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Acked-by: William Zhang <william.zhang@broadcom.com> Link: https://patch.msgid.link/20260803142003.12857-8-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: bcm63xx-hsspi: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use #ifdef guards. This has the advantage of always compiling these functions in, independently of any Kconfig option. Thanks to that, bugs and other regressions are subsequently easier to catch. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Acked-by: William Zhang <william.zhang@broadcom.com> Link: https://patch.msgid.link/20260803142003.12857-7-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: bcm-qspi: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use __maybe_unused. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://patch.msgid.link/20260803142003.12857-6-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: axiado: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use __maybe_unused. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://patch.msgid.link/20260803142003.12857-5-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: at91-usart: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use __maybe_unused. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://patch.msgid.link/20260803142003.12857-4-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: amlogic-spifc-a1: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use #ifdef guards. This has the advantage of always compiling these functions in, independently of any Kconfig option. Thanks to that, bugs and other regressions are subsequently easier to catch. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://patch.msgid.link/20260803142003.12857-3-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07spi: atmel-quadspi: use modern PM macrosJisheng Zhang
Use the modern PM macros for the suspend and resume functions to be automatically dropped by the compiler when CONFIG_PM or CONFIG_PM_SLEEP are disabled, without having to use __maybe_unused. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://patch.msgid.link/20260803142003.12857-2-jszhang@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2026-08-07perf sched latency: Add histogram and time interval optionsAaron Tomlin
While 'perf sched latency' reports task runtime and delay statistics (average and maximum delay), it does not provide a visual representation of how task wait times are distributed across latency ranges between snapshots (start and finish of the analysis window). The --histogram option collects CPU wait latencies (time between when a task becomes runnable and when it gets scheduled onto a CPU) into 22 latency buckets, displaying an ASCII bar chart distribution. The --hist-mode option configures the bucketing scheme: - log (default). Logarithmic latency buckets ranging from sub-microsecond (< 1 us) up to >= 1.05 seconds - linear. Equal-width linear latency buckets (i.e., 100 us steps up to >= 2.1 ms) The --time option allows filtering trace event processing to a specific time interval [start,stop]. Example histogram output excerpt: ❯ sudo perf sched latency --histogram --CPU 0 CPU Wait Latency Distribution Histogram (between snapshots) (total samples: 36114) ------------------------------------------------------------------- Latency Range | Count | Pct | Histogram Graph ------------------------------------------------------------------- < 1 us | 17 | 0.0% | # 2 - 4 us | 673 | 1.9% | # 4 - 8 us | 6237 | 17.3% | ###### 8 - 16 us | 3224 | 8.9% | ### 16 - 32 us | 1388 | 3.8% | # 32 - 64 us | 709 | 2.0% | # 64 - 128 us | 690 | 1.9% | # 128 - 256 us | 789 | 2.2% | # 256 - 512 us | 541 | 1.5% | # 512 - 1024 us | 2256 | 6.2% | ## 1 - 2 ms | 3577 | 9.9% | ### 2 - 4 ms | 13259 | 36.7% | ############## 4 - 8 ms | 2523 | 7.0% | ## 8 - 16 ms | 222 | 0.6% | # 16 - 32 ms | 10 | 0.0% | # >= 1.05 s | 3 | 0.0% | # ------------------------------------------------------------------- Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Aaron Tomlin <atomlin@atomlin.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2026-08-07perf sched latency: Auto-scale latency and runtime display unitsAaron Tomlin
Currently, 'perf sched latency' displays task runtime and delay values exclusively in milliseconds (ms). This can be hard to read when latencies are very small (in the microsecond or nanosecond range) or unusually large (seconds). Introduce auto-scaling for latency and runtime display columns. Values are dynamically scaled and output with the most appropriate unit: nanoseconds (ns), microseconds (us), milliseconds (ms), or seconds (s). Additionally, rename column headers from "Runtime ms", "Avg delay ms", and "Max delay ms" to "Runtime", "Avg delay", and "Max delay" respectively, adjust spacing to maintain column alignment and stripe redundant prefix strings from each row's format string to produce a clean, tabular output. For illustrative purposes, a comparison of the latency table header before and after this change is shown below: Before: ------------------------------------------------------------------------------------------------------------------------------------------- Task | Runtime ms | Count | Avg delay ms | Max delay ms | Max delay start | Max delay end | ------------------------------------------------------------------------------------------------------------------------------------------- kworker/2:2-mm_:154757 | 0.033 ms | 1 | avg: 0.829 ms | max: 0.829 ms | max start: 169486.543205 s | max end: 169486.544034 s After: ------------------------------------------------------------------------------------------------------------------------------------------ Task | Runtime | Count | Avg delay | Max delay | Max delay start | Max delay end | ------------------------------------------------------------------------------------------------------------------------------------------ kworker/2:2-mm_:154757 | 32.873 us | 1 | 829.347 us | 829.347 us | 169486.543205 s | 169486.544034 s | Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Aaron Tomlin <atomlin@atomlin.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2026-08-07perf sched: Handle missing trace samples in pipe modeAaron Tomlin
For pipe mode streams, event attributes are received dynamically during event processing, meaning session->evlist is not populated prior to perf_session__process_events(). To handle pipe input correctly: - Register the missing .attr, .tracing_data, .build_id, and .feature callbacks in cmd_sched() - Promote the handlers array to file-scope (latency_handlers[]) and dynamically assign matching tracepoint handlers (or process_sched_ignore) inside perf_sched__process_tracepoint_sample() when evsel->handler is NULL; replace process_sched_wakeup_ignore() with process_sched_ignore() - Perform the trace check post-processing when handling pipe data Fixes: 27295592c22e ("perf session: Share the common trace sample_check routine as perf_session__has_traces") Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Aaron Tomlin <atomlin@atomlin.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2026-08-07perf sched: Suppress latency table output when trace samples are missingAaron Tomlin
When 'perf sched latency' is executed on a perf.data file that lacks tracepoint samples (i.e., a file recorded without the -R flag or containing only non-tracepoint events), perf_session__has_traces() correctly outputs an error message. However, perf_sched__read_events() subsequently falls through and returns 0 (success). Consequently, caller functions such as perf_sched__lat() assume event processing succeeded and proceed to render empty latency header tables and total summary statistics. Fix this behaviour by ensuring perf_sched__read_events() aborts early and returns a suitable error code when perf_session__has_traces() evaluates to false. Additionally, validate thread__get_runtime() against NULL in map_switch_event() to prevent potential null-pointer dereferences. Fixes: 27295592c22e ("perf session: Share the common trace sample_check routine as perf_session__has_traces") Reviewed-by: Ian Rogers <irogers@google.com> Signed-off-by: Aaron Tomlin <atomlin@atomlin.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2026-08-07scsi: core: Fill in DMA padding bytes in scsi_alloc_sgtables()Petr Vaganov
During fuzz testing, the following issue was discovered: BUG: KMSAN: uninit-value in __dma_map_sg_attrs+0x217/0x310 __dma_map_sg_attrs+0x217/0x310 dma_map_sg_attrs+0x4a/0x70 ata_qc_issue+0x9f8/0x1420 __ata_scsi_queuecmd+0x1657/0x1740 ata_scsi_queuecmd+0x79a/0x920 scsi_queue_rq+0x4472/0x4f40 blk_mq_dispatch_rq_list+0x1cca/0x3ee0 __blk_mq_sched_dispatch_requests+0x458/0x630 blk_mq_sched_dispatch_requests+0x15b/0x340 __blk_mq_run_hw_queue+0xe5/0x250 __blk_mq_delay_run_hw_queue+0x138/0x780 blk_mq_run_hw_queue+0x4bb/0x7e0 blk_mq_sched_insert_request+0x2a7/0x4c0 blk_execute_rq+0x497/0x8a0 sg_io+0xbe0/0xe20 scsi_ioctl+0x2b36/0x3c60 sr_block_ioctl+0x319/0x440 blkdev_ioctl+0x80f/0xd70 __se_sys_ioctl+0x219/0x420 __x64_sys_ioctl+0x93/0xe0 x64_sys_call+0x1d6c/0x3ad0 do_syscall_64+0x4c/0xa0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Uninit was created at: __alloc_pages+0x5c0/0xc80 alloc_pages+0xe0e/0x1050 blk_rq_map_user_iov+0x2b77/0x6100 blk_rq_map_user_io+0x2fa/0x4d0 sg_io+0xad6/0xe20 scsi_ioctl+0x2b36/0x3c60 sr_block_ioctl+0x319/0x440 blkdev_ioctl+0x80f/0xd70 __se_sys_ioctl+0x219/0x420 __x64_sys_ioctl+0x93/0xe0 x64_sys_call+0x1d6c/0x3ad0 do_syscall_64+0x4c/0xa0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Bytes 14-15 of 16 are uninitialized Memory access of size 16 starts at ffff88800cbdb000 When processing the last unaligned element of the scatterlist, it is supplemented with missing bytes in the amount of pad_len. These bytes remain uninitialized, which leads to a problem. Extend last_sg->length by pad_len first, then use sg_zero_buffer() to zero those pad_len bytes. sg_zero_buffer() uses sg_miter internally, which correctly handles sg entries spanning multiple pages and padding that crosses a page boundary. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes: 40b01b9bbdf5 ("block: update bio according to DMA alignment padding") Cc: stable@vger.kernel.org Signed-off-by: Petr Vaganov <p.vaganov@ideco.ru> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://patch.msgid.link/20260628185229.37957-1-p.vaganov@ideco.ru Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
2026-08-07Merge patch series "scsi: zfcp: Enable CONTEXT_ANALYSIS"Martin K. Petersen (Oracle)
Heiko Carstens <hca@linux.ibm.com> says: Enable CONTEXT_ANALYSYS for the zfcp driver. Static code checking for acquiring and releasing locks used to be done with sparse. That was removed with [1] and replaced with a clang based approach [2]. The new approach requires that each subsystem needs to be explicitly enabled for checking. Do that for drivers/s390/scsi. Add a __must_hold() attribute to zfcp_qdio_sbal_get() to address the only valid warning. Then enable CONTEXT_ANALYSIS, similar to other patches for drivers/s390 I'm currently working on. Link: https://patch.msgid.link/20260806134759.2122369-1-hca@linux.ibm.com Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
2026-08-07Merge branches 'acpi-processor', 'acpi-ec', 'acpi-fan' and 'acpi-battery'Rafael J. Wysocki
Merge updates of the ACPI processor, EC, fan, and battery drivers for 7.3-rc1: - Unregister the cpufreq notifier on init failure in the ACPI processor driver (Can Peng) - Validate MADT IOAPIC entry bounds during IOAPIC hotplug lookup in the ACPI processor driver (Pengpeng Hou) - Avoid _REG disconnect on probe deferrals related to GPIO IRQ in the ACPI EC driver (Zhu Ling) - Use a correct function parameter name in kernel-doc in the ACPI fan driver (Randy Dunlap) - Update ACPI fan IDs to follow modern style and clean up header file inclusions in the ACPI fan driver (Andy Shevchenko) - Use devm_acpi_install_notify_handler() to replace a custom open-coded devres-based management of an ACPI notify handler in the ACPI fan driver (Rafael Wysocki) - Adjust charging status validation check in the ACPI battery driver to avoid incorrect status reporting (Rafael Wysocki) - Merge consecutive battery notifications in the ACPI battery driver to reduce the pressure on STA, _BST and _BIX/_BIF ACPI control methods and make that driver use kstrtoul() instead of sscanf("%lu\n") (Rong Zhang) - Sanitise model_number in the ACPI battery driver by dropping unprintable characters (Kate Hsuan) * acpi-processor: ACPI: processor: Unregister cpufreq notifier on init failure ACPI: processor: validate MADT IOAPIC entry bounds * acpi-ec: ACPI: EC: Avoid _REG disconnect on GPIO IRQ defer * acpi-fan: ACPI: fan: Use correct function parameter name in kernel-doc ACPI: fan: Update ACPI fan IDs to follow modern style ACPI: fan: Don't use "proxy" headers ACPI: fan: Use devm_acpi_install_notify_handler() * acpi-battery: ACPI: battery: Adjust charging status validation check ACPI: battery: Use kstrtoul() over sscanf("%lu\n") ACPI: battery: Merge consecutive battery notifications ACPI: battery: Sanitise model_number by dropping unprintable characters
2026-08-07scsi: zfcp: Enable CONTEXT_ANALYSISHeiko Carstens
The zfcp driver passes clang's compile time context analysis. Therefore enable CONTEXT_ANALYSIS. Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Link: https://patch.msgid.link/20260806134759.2122369-3-hca@linux.ibm.com Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
2026-08-07scsi: zfcp: Add __must_hold() attribute to zfcp_qdio_sbal_get()Heiko Carstens
Add __must_hold() attribute to zfcp_qdio_sbal_get() in order to let clang's context analysis know that qdio->req_q_wq must be held on function entry. This is also documented above the function. Without this annotation this leads to a valid warning when context analysis is enabled: drivers/s390/scsi/zfcp_qdio.c:287:8: warning: expecting spinlock '->req_q_lock' to be held at start of each loop [-Wthread-safety-analysis] 287 | ret = wait_event_interruptible_lock_irq_timeout(qdio->req_q_wq, | ^ Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Link: https://patch.msgid.link/20260806134759.2122369-2-hca@linux.ibm.com Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
2026-08-07scsi: fnic: Use GFP_ATOMIC for VLAN alloc under spinlockLinkai Gong
fnic_fcoe_process_vlan_resp() allocates a VLAN descriptor with kzalloc_obj() (default GFP_KERNEL) while holding vlans_lock via spin_lock_irqsave(). GFP_KERNEL may sleep, which is not allowed in this atomic context and can trigger a sleeping-from-invalid-context warning or deadlock. Pass GFP_ATOMIC so the allocation is safe under the IRQ-safe spinlock. Fixes: 098585aa8aca ("scsi: fnic: Add and integrate support for FIP") Cc: stable@vger.kernel.org Signed-off-by: Linkai Gong <gonglinkai@kylinos.cn> Reviewed-by: Karan Tilak Kumar <kartilak@cisco.com> Link: https://patch.msgid.link/20260731073820.16449-1-gonglinkai@kylinos.cn Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
2026-08-07scsi: storvsc: Support manual scans for all Hyper-V targetsLaurence Oberman
The Fibre Channel transport topology created by storvsc exposes only one dummy remote port per SCSI host. Its scsi_target_id is always zero. As a result, the FC transport user-scan path looks up the remote port using target ID 0. It cannot initiate a scan for Target 1 or higher. No SCSI command is therefore sent to Hyper-V when userspace explicitly requests a scan of one of these targets. storvsc itself supports up to STORVSC_FC_MAX_TARGETS and already passes scmnd->device->id to Hyper-V as vm_srb->target_id. Devices on Target 1 and higher work when initially discovered. They can also be rediscovered by a full host scan, such as the scan triggered after an FC port bounce. Provide a storvsc-specific user_scan callback that uses the exported scsi_scan_target() interface. Iterate over the requested channel and target ranges so that wildcard and explicitly addressed scans retain the expected SCSI sysfs scan semantics. This bypasses the single-rport lookup in fc_user_scan() and allows userspace to explicitly scan any target supported by storvsc without requiring one synthetic fc_rport for every Hyper-V target. Signed-off-by: Laurence Oberman <loberman@redhat.com> Link: https://patch.msgid.link/20260723163743.1274830-1-loberman@redhat.com Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
2026-08-07ACPI: APEI: Handle repeated SEA error stormsJunhao He
When hardware memory corruption occurs and a user process accesses the corrupted page, the CPU triggers a Synchronous External Abort (SEA). The kernel invokes do_sea() to handle the exception, which calls memory_failure() to handle the faulty page. Scenario 1: Memory Error Interrupt First, then SEA The page is already poisoned by the memory error interrupt path. The subsequent SEA handler sends a SIGBUS to the task, which accesses the poisoned page. This flow is correct. Scenario 2: SEA first, then memory error interrupt (problematic scenario) If a user task directly accesses corrupted memory through a PFNMAP-style mapping (e.g., devmem), the page may still be in the free-buddy state when SEA is handled. In this case, memory_failure() will poison the page without invoking kill_accessing_process(), and then takes the free-buddy recovery path. After the CPU returns to the task context, the task re-enters the SEA handler due to the same access. However, ghes_estatus_cached() suppresses all subsequent entries during the 10-second window, preventing ghes_do_proc() from being called. This suppression blocks the MF_ACTION_REQUIRED-based SIGBUS delivery, causing the kernel to fail to kill the task immediately. Consequently, the process keeps re-entering the SEA handler, leading to an SEA storm. Later, the memory error interrupt path also cannot kill the task, leaving the system stuck in this repeated loop. The following error logs are explained using the devmem process: NOTICE: SEA Handle [Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 9 [Hardware Error]: event severity: recoverable [Hardware Error]: section_type: ARM processor error [Hardware Error]: physical fault address: 0x0000001000093c00 [T54990] Memory failure: 0x1000093: recovery action for free buddy page: Recovered [ T9955] EDAC MC0: 1 UE Multi-bit ECC on unknown memory (page:0x1000093 offset:0xc00 grain:1 - APEI location: ...) NOTICE: SEA Handle NOTICE: SEA Handle ... ... ---> SEA storm ... NOTICE: SEA Handle [ T9955] Memory failure: 0x1000093: already hardware poisoned ghes_print_estatus: 1 callbacks suppressed [Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 9 [Hardware Error]: event severity: recoverable [Hardware Error]: section_type: ARM processor error [Hardware Error]: physical fault address: 0x0000001000093c00 [T54990] Memory failure: 0x1000093: already hardware poisoned [T54990] 0x1000093: Sending SIGBUS to devmem:54990 due to hardware memory corruption To resolve this, return an error when encountering the same SEA again. The subsequent SEA handler invocation uses arm64_notify_die() to send a SIGBUS signal to the task, which terminates the process and prevents it from re-entering the handler loop. Signed-off-by: Junhao He <hejunhao3@h-partners.com> Reviewed-by: Wupeng Ma <mawupeng1@huawei.com> Reviewed-by: Shuai Xue <xueshuai@linux.alibaba.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Link: https://patch.msgid.link/20260527082707.2013499-1-hejunhao3@h-partners.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2026-08-07ACPI: APEI: Fix ERST timeout unit conversionNirmoy Das
The ACPI specification defines bits 63:32 returned by GET_EXECUTE_OPERATION_TIMINGS as the maximum execution time in microseconds. erst_get_timeout() instead multiplies the value by NSEC_PER_MSEC. Use NSEC_PER_USEC to express the firmware-provided microsecond timeout in the nanosecond units expected by erst_timedout(). Fixes: fac475aab70b ("ACPI: APEI: Use ERST timeout for slow devices") Cc: stable@vger.kernel.org Signed-off-by: Nirmoy Das <nirmoyd@nvidia.com> Reviewed-by: Hanjun Guo <guohanjun@huawei.com> Link: https://patch.msgid.link/20260721182551.2434933-1-nirmoyd@nvidia.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2026-08-07fwctl/bnxt: Add DMA buffer support for HWRM commandsPavan Chebbi
Several HWRM commands carry __le64 DMA address fields in their input structures; firmware reads from or writes to the memory those addresses point to. Have a static per-command descriptor table in the driver that records the details of the DMA fields in each supported HWRM input struct. When a DMA-bearing HWRM command arrives, the driver reads the userspace pointer out of each declared address field and clears the field, allocates a DMA-coherent kernel buffer sized from the command's own length information, copies data to/from the userspace pointer, and patches the field with the real DMA bus address before the command is sent to firmware. Responses are copied back to the original userspace pointer afterward. Scope-gated allow-list and timeout value list are updated with the new the commands. Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com> Link: https://patch.msgid.link/20260807125846.45570-3-pavan.chebbi@broadcom.com Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
2026-08-07bnxt_en: Update bnxt firmware specPavan Chebbi
Since bnxt_fwctl is going to support additional commands in the next patch, add their missing definitions from the firmware spec. Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com> Link: https://patch.msgid.link/20260807125846.45570-2-pavan.chebbi@broadcom.com Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
2026-08-07btrfs: skip hole detection during full fsync for files without holesFilipe Manana
If we the no-holes feature is enabled (a default since btrfs-progs 5.15), when doing a full fsync we always iterate of all leaves in the subvolume root that contain file extent items in order to detect holes between them. This can take a lot of time for files with a large number of extents. But if we know there are no prealloc extents and the amount of space (uncompressed space) is greater than or equals to the i_size of the inode, then we cannot have holes and therefore avoid searching for them. So skip the search if those conditions are met. The following test script was used: $ cat test.sh #!/bin/bash MNT=/mnt/nullb0 DEV=/dev/nullb0 umount $MNT &> /dev/null mkfs.btrfs -f $DEV mount $DEV $MNT # 256M gives 64K extents of 4K each. FILE_SIZE=$((256 * 1024 * 1024)) touch $MNT/foobar for ((i = 0; i < $FILE_SIZE; i += 8192)); do xfs_io -c "pwrite -S 0xab $i 4K" $MNT/foobar > /dev/null done xfs_io -c "fsync" $MNT/foobar for ((i = 4096; i < $FILE_SIZE; i += 8192)); do xfs_io -c "pwrite -S 0xab $i 4K" $MNT/foobar > /dev/null done # unmount and mount, clear caches and ensure the next fsync is a # full sync. umount $MNT mount $DEV $MNT # Do some change to the file in order to fsync. xfs_io -c "pwrite -S 0xcd 0 4K" $MNT/foobar > /dev/null T0=$(date +%s%N) xfs_io -c "fsync" $MNT/foobar T1=$(date +%s%N) echo echo "Took $(( (T1 - T0) / 1000 ))us" umount $MNT Before this change: Took 28721us After this change: Took 5453us That's about 5.3x times faster. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: add extra ASSERT()s to make sure the folio size is correctQu Wenruo
Inspired by the previous crash exposed by generic/795, we want to make sure every folio from btrfs page cache is properly aligned to block size. This is especially important for bs > ps support, as every btrfs infrastructure, e.g. extent map and extent state, requires strong block alignment checks. Furthermore, also output the minimal folio order from the inode mapping, which is the determining factor during debugging, helping a lot pinning down the final cause. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: use GFP_NOWAIT for tree block readaheadBoris Burkov
extent_buffer readahead should not be able to painfully stall a search_slot and hog tree locks by getting stuck in direct reclaim. If the allocation fails, that is fine, we simply fail to do the readahead in that case. Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: enable unlocked NOFAIL retry for eb allocationsBoris Burkov
Now that we have the btrfs_eb_prealloc struct to carry the allocation and the "needs prealloc" signal, wire that up between the various search_slot style callers down into alloc_extent_buffer. If the prealloc struct indicates that it supports a nowait try, then alloc_extent_buffer tries to allocate NOWAIT. If that succeeds, great. Otherwise, we return EAGAIN and signal via the struct that preallocation is required. The caller then does the allocation and tries again with the eb, bfs, and folios wired through in the prealloc struct. If unlock-and-allocate retries are not supported then we just use the normal gfp flags like before. Note that there are still two GFP_NOFS allocations, as far as I know, that happen under the lock and cannot be preallocated: - the __xa_cmpxchg to insert the eb into the eb xarray - the xarray allocations for filemap_add_folio to add the folios to the btree_inode mapping. The former we could wire up with xa_reserve if we signaled the "prealloc start" back up to the retry point. However, since there is no concept of reservation in the filemap xarray, it seemed relatively unhelpful to bother. These allocations are relatively small cached slab allocations, so hopefully we can move the needle on reclaim stalls without reserving them. Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: add struct btrfs_eb_preallocBoris Burkov
In further preparation for supporting NOFAIL allocations with retries outside the critical section, add a struct to carry the extent_buffer and btrfs_folio_state we need to allocate. Refactor the allocation pathways to use the new struct but with no functional change. Wire empty prealloc structs in from callers. Reviewed-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: factor init_extent_buffer from __alloc_extent_bufferBoris Burkov
In preparation for preallocating extent_buffer data, factor eb initialization away from specifically allocating it. This allows us to allocate the eb, bfs, folios, etc. together in the main search_slot code paths, but still share initialization code with the dummy/test/clone allocation paths. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: qgroup: fix a wrong length calculation in qgroup_free_reserved_data()Qu Wenruo
In that function, we round down the start position and round up the ending position. But during the calculation of @len, we use "round_up(start + len, sectorsize)", which is the rounded up end position, not the rounded up length. Which results a much larger length, and later we are still using "start + len", which is completely incorrect. Fix it by declaring a local @aligned_start and @aligned_len and use them instead. Fixes: bc42bda22345 ("btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges") Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: add validation for extent statesQu Wenruo
Extent maps have the extra validation since commit 3f255ece2f1e ("btrfs: introduce extra sanity checks for extent maps"), but extent states do not have a similar check. Introduce a basic alignment check for the following call sites, so that we can cover all extent states inserted into the tree: - insert_state_fast() - insert_state() - split_state() Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: use aligned range for locking in reflinkQu Wenruo
In btrfs_extent_same_range() and btrfs_clone_files(), the range passed into btrfs_lock_extent() is not aligned at its end, because we can reflink until the EOF, which may not be block aligned. Although this is not a big deal, for the sake of consistency, and to prepare for the upcoming stricter alignment check, pass an aligned range end to btrfs_lock_extent() and btrfs_unlock_extent(). Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: use aligned range for locking in extent_fiemap()Qu Wenruo
The @end parameter for all extent io tree helpers is inclusive, but the call site in extent_fiemap() is passing an exclusive end into btrfs_lock_extent(), which will step into the next block unexpectedly. Pass the inclusive end into btrfs_lock_extent() and btrfs_unlock_extent(). Fixes: ac3c0d36a2a2 ("btrfs: make fiemap more efficient and accurate reporting extent sharedness") Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: zoned: don't clobber the extent buffer when zeroing it outJohannes Thumshirn
On a zoned filesystem a freed-but-still-dirty tree block is written out as zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write pointer advancing. btree_csum_one_bio() implemented this by memzeroing the extent buffer's own folios before submission. That destroys the in-memory buffer while it may still be referenced. In particular btrfs_free_tree_block() can run on it afterwards and reads the header to add a delayed reference; once the header has been zeroed it frees bytenr 0 and corrupts the extent tree (the btrfs_header_bytenr(buf) != 0 ASSERT in btrfs_free_tree_block(), or an "unable to find ref" abort). It is flaky and reproduces under fsstress, e.g. generic/461 and generic/013. Write the zeros to disk from the shared zero page instead and leave the extent buffer content untouched, so any later reference - including the delayed reference from btrfs_free_tree_block() - still sees a valid header. end_bbio_meta_write() now clears writeback on the buffer's own folios, as the bio no longer carries them. Fixes: aa6313e6ff2b ("btrfs: zoned: don't clear dirty flag of extent buffer") Assisted-by: LLM (debugging, commit message) Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: zoned: drop stranded dirty metadata buffers at unmountJohannes Thumshirn
On a zoned filesystem a freed tree block is kept dirty and flagged EXTENT_BUFFER_ZONED_ZEROOUT so a later writeback zeroes it out and advances the zone write pointer. Unsynced tree-log updates (e.g. from rename or link) leave such buffers behind when the log is freed at commit, and across log generations they can end up ahead of the write pointer behind a hole, so btree_writepages() can never write them. During normal operation the space is later reclaimed by a zone reset; at unmount it is not, and the buffers survive to the final iput() of the btree inode, which hangs in folio_wait_writeback() once the endio workqueues are stopped. They cannot be written back from where they are freed (free_log_tree(), inside the committing transaction) without deadlocking against that commit, and they are stale anyway, not referenced by the committed superblock. Drop their dirty state in close_ctree(), before btrfs_stop_all_workers(). Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: zoned: drop stranded dirty metadata on transaction abortJohannes Thumshirn
On a zoned filesystem a freed tree block is not cleared but kept dirty and flagged EXTENT_BUFFER_ZONED_ZEROOUT, so a later writeback zeroes it out and advances the zone write pointer. A transaction abort turns the filesystem read-only before that writeback runs, so these buffers stay dirty and stranded ahead of the write pointer where btree_writepages() can no longer write them. They survive to the final iput() of the btree inode at unmount, which submits the write after the endio workqueues are gone, hanging unmount in folio_wait_writeback(). Clear the dirty state of such buffers when cleaning up the aborted transaction, where the buffer tree still references all of them. Assisted-by: LLM (debugging, commit message) Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: zoned: flush active metadata block group at btree_writepages() startJohannes Thumshirn
btree_writepages() writes the btree inode's dirty metadata in ascending logical address order. On a zoned filesystem only one metadata and one system block group is active for writing at a time, and check_bg_is_active() (via btrfs_check_meta_write_pointer()) pivots the active block group as writeback moves from one block group to the next. If the active block group sits at a higher logical address than another block group that also holds dirty metadata, the ascending walk reaches the lower one first and, to write it, has to finish the active block group and activate the lower one. It cannot finish a block group that still has unsent IO, and during WB_SYNC_ALL && !for_sync (commit) writeback it deliberately refuses to wait for that IO under fs_info->zoned_meta_io_lock, as that can deadlock. The pivot thus cannot issue the submission itself either, so it gives up: btrfs_check_meta_write_pointer() returns -EAGAIN, which btrfs_write_and_wait_transaction() treats as fatal and aborts the transaction, forcing the filesystem read-only. This happens intermittently under metadata-heavy relocation (e.g. fstests btrfs/187). Flush the active metadata and system block groups at the start of btree_writepages(), under the fs_info->zoned_meta_io_lock it already holds, so they have no unsent IO left and the later pivot can finish them and make forward progress. Fixes: 13bb483d32ab ("btrfs: zoned: activate metadata block group on write time") Assisted-by: LLM (debugging, commit message) Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: convert reflink.c to use btrfs_inode as parametersQu Wenruo
Inside reflink.c we still have a lot of functions passing VFS inode pointers, then internally convert them into btrfs_inode pointers. For example, inside btrfs_clone(), we have 12 BTRFS_I() call sites, while only 3 callsites that really require a VFS inode pointer. Do the cleanup to convert the following functions to pass a btrfs_inode pointer instead of a vanilla inode pointer: - btrfs_clone() - btrfs_extent_same_range() - clone_finish_inode_update(). Which covers all ad-hoc BTRFS_I() call sites inside reflink.c. Reviewed-by: Daniel Vacek <neelx@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: use simple booleans for log_commit field in struct btrfs_rootFilipe Manana
We are using atomic types for the log_commit array of struct btrfs_root but all we need is simple booleans. The log_commit array elements are always protected by the root's log_mutex, both for writes and reads, so we can use a simple boolean. The use of atomics if from the very early days of the log tree code where the access to the fields was not protected by any lock. So switch to simple booleans, which results in cheaper code and slightly reduces the object size too. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: check for exit condition after waking in wait_log_commit()Filipe Manana
We check for the exit condition after we add ourselves to the wait queue and before we unlock the root's log_mutex, sleep and lock again log_mutex. This is not incorrect, but it's not optimal since in the first iteration this is pointless because we already know that root->log_commit[index] is not zero, so we should check the exit condition only after unlocking log_mutex, sleeping, waking up and locking again the log_mutex. So move the check for the exit condition to bottom of the loop, after we were woken and locked log_mutex again. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: move condition for log commit wait into wait_log_commit()Filipe Manana
Instead of having every caller check for root->log_commit[] being non-zero and then call wait_log_commit(), move the check into wait_log_commit() and have the callers call it unconditionally. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: remove log batch counter use for fsyncFilipe Manana
We have the log batch counter defined per root which is now useless after the previous patch (titled: "btrfs: stop sleeping for one jiffy in non-ssd mounts during log commit"). The counter is incremented early in the fsync path, before and after flushing dellaloc and waiting for writeback, and then the counter is read during the log sync path. The goal was to wait for tasks that are about to join a log transaction, so that we could reduce the amount of IO and log syncing (flush all log tree extent buffers and write super blocks), but that mechanism does not work since if there are currently no log writers, btrfs_sync_log() does not unlock the root's log_mutex, so no new log writers can join the log transaction. Having concurrent fsync tasks increasing the log_batch counter only makes us loop unnecessarily in btrfs_sync_log() - that is always true since the previous patch mentioned above and was true before that patch only when not using the "-o ssd" mount option (which is activated by default if the filesystem does not have rotational devices). So remove the log batch counter. No performance changes were observed after removing it. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: stop sleeping for one jiffy in non-ssd mounts during log commitFilipe Manana
Joining/starting a log transaction tracks if we ever had more than one task concurrently logging by setting the flag BTRFS_ROOT_MULTI_LOG_TASKS in the respective root. Once set, this flag remains for the rest of the lifetime of the transaction, only cleared when we don't have a log root and need to create a new one (transaction commits drop log roots). During log commit, if we are not on a ssd mount (or use the -o nossd mount option) and the BTRFS_ROOT_MULTI_LOG_TASKS flag is set, we sleep for one jiffy with the excuse to allow future log writers to join and log inodes and then commit a larger log transaction to reduce overall IO. However this is extremely inefficient because: 1) If at some point we had multiple tasks logging concurrently but now we have only one task at a time, we force it to wait for 1 jiffy; 2) One jiffy can vary between 1ms to 10ms, depending on the kernel config option CONFIG_HZ, which by default has a value of 250HZ and that corresponds to 4ms - that is a lot. This massively reduces the latency of fsyncs for non-ssd mounts, even on consumer grade spinning disks. Remove this mechanism to track if we have (or ever had) multiple tasks logging and wait for 1 jiffy. The following fio test was used to benchmark: $ cat fio-buffered-fsync.sh DEV=/dev/sdj MNT=/mnt/sdj MOUNT_OPTIONS="" MKFS_OPTIONS="" if [ $# -ne 6 ]; then echo "Use $0 NUM_JOBS FILE_SIZE IO_SIZE FSYNC_FREQ BLOCK_SIZE [write|randwrite]" exit 1 fi NUM_JOBS=$1 FILE_SIZE=$2 IO_SIZE=$3 FSYNC_FREQ=$4 BLOCK_SIZE=$5 WRITE_MODE=$6 if [ "$WRITE_MODE" != "write" ] && [ "$WRITE_MODE" != "randwrite" ]; then echo "Invalid WRITE_MODE, must be 'write' or 'randwrite'" exit 1 fi cat <<EOF > /tmp/fio-job.ini [writers] rw=$WRITE_MODE fsync=$FSYNC_FREQ fallocate=none group_reporting=1 direct=0 bs=$BLOCK_SIZE ioengine=psync filesize=$FILE_SIZE io_size=$IO_SIZE directory=$MNT numjobs=$NUM_JOBS EOF echo echo "Using config:" echo cat /tmp/fio-job.ini echo umount $MNT &> /dev/null mkfs.btrfs -f $MKFS_OPTIONS $DEV mount $MOUNT_OPTIONS $DEV $MNT fio /tmp/fio-job.ini umount $MNT Running the script as: ./fio-buffered-fsync.sh 8 64M 64M 1 4K randwrite Before patch: WRITE: bw=2647KiB/s (2711kB/s), 2647KiB/s-2647KiB/s (2711kB/s-2711kB/s), io=512MiB (537MB), run=198055-198055msec After patch: WRITE: bw=14.9MiB/s (15.6MB/s), 14.9MiB/s-14.9MiB/s (15.6MB/s-15.6MB/s), io=512MiB (537MB), run=34471-34471msec That's about 5.7 times faster. Reviewed-by: Boris Burkov <boris@bur.io> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: sysfs: fix path of the "read_policy" module parameter in commentZenghui Yu
The correct path of the "read_policy" module parameter should be /sys/module/btrfs/parameters/read_policy. Fix it. Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Zenghui Yu <zenghui.yu@linux.dev> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: retry verity reads for not-uptodate Merkle foliosYichong Chen
btrfs_read_merkle_tree_page() can find a folio in the mapping that is not uptodate. After taking the folio lock, the current code treats that state as a read error and returns -EIO. That can make a previous transient read failure sticky. If the failed read left a not-uptodate folio in the mapping, later callers find that folio and fail instead of retrying the read. Keep the existing page-cache insertion and locking order, but retry the Merkle item read when a not-uptodate folio is found in the mapping. Also unlock the folio when read_key_bytes() fails so that a later caller can lock it and retry the read. Fixes: 06ed09351b67 ("btrfs: convert btrfs_read_merkle_tree_page() to use a folio") Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Yichong Chen <chenyichong@uniontech.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: use %pe for error code outputQu Wenruo
During an interrupted mount, I got the following messages: workqueue: Failed to create a rescuer kthread for wq "btrfs-qgroup-rescan": -EINTR BTRFS error (device dm-3): open_ctree failed: -12 Workqueue code is outputting a human readable error string, meanwhile we're still using a numeric error code. So follow the workqueue code to use "%pe" format, which will automatically convert an error pointer to the human readable string. However this is a minor pitfall, if the return value is not an error code, e.g. a positive number, "%pe" with "ERR_PTR(ret)" will output the pointer as a hash value, e.g.: ret=1 %pe out=0000000019414716 ret=-22 %pe out=-EINVAL So we should not use this "%pe" output for callsites that are known to return positive values. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: open code BTRFS_BYTES_TO_BLKS()Qu Wenruo
That macro is only utilized 4 times, all inside file.c, while we have tons of open-coded usages. And since it's a macro, there is no proper type checks at all. There isn't much need for such a rarely utilized macro. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: replace writeback inhibition xarray with a fixed inline bufferLeo Martins
Commit f9a48549a15a ("btrfs: inhibit extent buffer writeback to prevent COW amplification") tracks the extent buffers a transaction handle has inhibited in a per-handle xarray. Keying the tracking to the transaction handle is correct, but using an xarray for it causes two problems in production. First, a write_iops regression. Every COW calls btrfs_inhibit_eb_writeback() from btrfs_force_cow_block() and should_cow_block(), which does an xa_store() keyed by eb->start. The kernel test robot reported a 22.6% fio.write_iops regression on a single-task 4k randwrite workload (ftruncate ioengine, buffered IO) on btrfs. The cost is the per-COW xarray store done on every COW'd block. Replacing it with a non-allocating fixed buffer recovers the lost throughput, and that buffer does more per-COW bookkeeping yet still recovers, so the cost is the xarray operation itself rather than the extra tracking work. Second, an unbounded cleanup walk. btrfs_uninhibit_all_eb_writeback() iterates every eb the handle inhibited with xa_for_each(). A single handle that COWs a very large number of blocks (inode eviction, or truncate of a file with many extents, where btrfs_truncate_inode_items() loops over many search_again descents under one handle) makes that walk arbitrarily long. It runs in __btrfs_end_transaction() before num_writers is dropped, so it blocks the committing thread; this shows up as multi-second stalls and RCU stall reports. Replace the xarray with a fixed inline array on btrfs_trans_handle, managed with a CLOCK (second-chance) eviction policy. Inhibiting a buffer becomes an array append with no allocation and no tree walk, and the end-of-handle cleanup is bounded by the array size. The set that actually needs protection is the working set the handle revisits across search_again descents, the search path frontier, which is on the order of the tree height. It is not every block the handle ever COWs. should_cow_block() re-inhibiting an already tracked buffer marks it referenced, so revisited buffers survive eviction while write-once buffers are reclaimed first. A small fixed buffer is therefore enough where a non-evicting array would either overflow or have to grow without bound. BTRFS_INHIBITED_EBS_SLOTS is 8 and the reference bits pack into a u32. The CLOCK eviction is what justifies the extra complexity over a plain non-evicting array. The test workload stresses amplification: it removes 16 heavily fragmented 64 MiB files in one transaction while background writeback keeps writing out in-use metadata. A re-COW event is a buffer already COWed in the running transaction that was written back and then COWed again; the figure below is the ratio of re-COW events to first-COW events summed across the eviction (n=5, lower is better): tracking re-COW per first-COW no inhibition 6.1 non-evicting array, 32 slots 3.8 CLOCK array, 8 slots (this patch) 1.6 unbounded xarray (reverted) 1.4 The non-evicting array fills with write-once buffers and stops covering the buffers the handle keeps revisiting, so even at four times the slots it leaves most of the amplification. CLOCK evicts the cold buffers and keeps the revisited ones, recovering almost all of the unbounded benefit. The eviction policy, not the buffer size, is what closes the gap. eb->writeback_inhibitors and the WB_SYNC_ALL bypass in lock_extent_buffer_for_io() are unchanged, so fsync and commit behavior are unaffected. A reference is taken on each tracked buffer so it cannot be freed while the array points at it; eviction drops that reference and the inhibitor count. There's another testing report, showing 20% latency improvement on reflink and deduplication synthetic benchmark. Full detailed report at https://github.com/lcf0399/linux-regression-evidence/tree/main/btrfs-remap-writeback-inhibition-v2 . Link: https://lore.kernel.org/all/CANGjgd=fQkHht2PdDi-+EAdzWH7UtxxWhhJ7b80Rr17PbpgxOw@mail.gmail.com/ Reported-by: kernel test robot <oliver.sang@intel.com> Fixes: f9a48549a15a ("btrfs: inhibit extent buffer writeback to prevent COW amplification") Closes: https://lore.kernel.org/oe-lkp/202603112240.f7605968-lkp@intel.com Tested-by: Chengfeng Lin <lin2530632123@gmail.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Sun YangKai <sunk67188@gmail.com> Signed-off-by: Leo Martins <loemra.dev@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: compression: allocate heuristic buckets with workspaceRosen Penev
Avoid allocating the heuristic buckets separately from the workspace, the lifetime is the same. The new size of struct heuristic_ws is 2112. SLUB merges same/similar sized structures for the named caches, so there's a chance such size already exists on the system, like below: $ grep 2112 /proc/slabinfo sighand_cache 593 1335 2112 15 8 Signed-off-by: Rosen Penev <rosenp@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2026-08-07btrfs: check if root is readonly when setting posix aclSun YangKai
For a filesystem which has btrfs read-only property set to true, all write operations including acl and xattr should be denied. However, acl can still be set even if btrfs ro property is true. This happens because no function on the set_acl code path checks the root is readonly or not. It was checked in btrfs_setxattr_trans() but got removed in commit 353c2ea735e4 ("btrfs: remove redundant readonly root check in btrfs_setxattr_trans") That commit didn't check if all the callers properly check the root's read-only flag. A previous fix is commit b51111271b03 ("btrfs: check if root is readonly while setting security xattr"). Always check if the root is read-only before performing the set acl operation. Fixes: 353c2ea735e4 ("btrfs: remove redundant readonly root check in btrfs_setxattr_trans") Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Sun YangKai <sunyangkai@fnnas.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>