kernel/linux.git/include/linux/backing-dev.h, branch v6.6.132

writeback: fix false warning in inode_to_wb()

2025-04-25T08:45:45+00:00

commit 9e888998ea4d22257b07ce911576509486fa0667 upstream. inode_to_wb() is used also for filesystems that don't support cgroup writeback. For these filesystems inode->i_wb is stable during the lifetime of the inode (it points to bdi->wb) and there's no need to hold locks protecting the inode->i_wb dereference. Improve the warning in inode_to_wb() to not trigger for these filesystems. Link: https://lkml.kernel.org/r/20250412163914.3773459-3-agruenba@redhat.com Fixes: aaa2cacf8184 ("writeback: add lockdep annotation to inode_to_wb()") Signed-off-by: Jan Kara Signed-off-by: Andreas Gruenbacher Reviewed-by: Andreas Gruenbacher Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

writeback: remove unused delaration of bdi_async_bio_wq

2023-08-21T20:38:01+00:00

It seems it was introduced by commit d3f77dfdc718 ("blkcg: implement REQ_CGROUP_PUNT") unintentionally, but the definition does not exist, remove it. Link: https://lkml.kernel.org/r/20230812110128.482650-1-xiujianfeng@huaweicloud.com Signed-off-by: Xiu Jianfeng Acked-by: Tejun Heo Cc: Stefan Roesch Signed-off-by: Andrew Morton

mm: add bdi_set_min_ratio_no_scale() function

2022-11-30T23:59:06+00:00

This introduces bdi_set_min_ratio_no_scale(). It uses the max granularity for the ratio. This function by the new sysfs knob min_ratio_fine. Link: https://lkml.kernel.org/r/20221119005215.3052436-19-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: add bdi_set_max_ratio_no_scale() function

2022-11-30T23:59:06+00:00

This introduces bdi_set_max_ratio_no_scale(). It uses the max granularity for the ratio. This function by the new sysfs knob max_ratio_fine. Link: https://lkml.kernel.org/r/20221119005215.3052436-16-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: add bdi_set_min_bytes() function

2022-11-30T23:59:05+00:00

This introduces the bdi_set_min_bytes() function. The min_bytes function does not store the min_bytes value. Instead it converts the min_bytes value into the corresponding ratio value. Link: https://lkml.kernel.org/r/20221119005215.3052436-13-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: add bdi_get_min_bytes() function

2022-11-30T23:59:05+00:00

This adds a function to return the specified value for min_bytes. It converts the stored min_ratio of the bdi to the corresponding bytes value. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The returned value can be different than the value when the min_bytes value was set. Link: https://lkml.kernel.org/r/20221119005215.3052436-11-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: add bdi_set_max_bytes() function

2022-11-30T23:59:04+00:00

This introduces the bdi_set_max_bytes() function. The max_bytes function does not store the max_bytes value. Instead it converts the max_bytes value into the corresponding ratio value. Link: https://lkml.kernel.org/r/20221119005215.3052436-8-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: add bdi_get_max_bytes() function

2022-11-30T23:59:04+00:00

This adds a function to return the specified value for max_bytes. It converts the stored max_ratio of the bdi to the corresponding bytes value. It introduces the bdi_get_bytes helper function to do the conversion. This is an approximation as it is based on the value that is returned by global_dirty_limits(), which can change. The helper function will also be used by the min_bytes bdi knob. Link: https://lkml.kernel.org/r/20221119005215.3052436-6-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: use part per 1000000 for bdi ratios

2022-11-30T23:59:03+00:00

To get finer granularity for ratio calculations use part per million instead of percentiles. This is especially important if we want to automatically convert byte values to ratios. Otherwise the values that are actually used can be quite different. This is also important for machines with more main memory (1% of 256GB is already 2.5GB). Link: https://lkml.kernel.org/r/20221119005215.3052436-5-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Chris Mason Cc: Jens Axboe Signed-off-by: Andrew Morton

mm: add bdi_set_strict_limit() function

2022-11-30T23:59:03+00:00

Patch series "mm/block: add bdi sysfs knobs", v4. At meta network block devices (nbd) are used to implement remote block storage. In testing and during production it has been observed that these network block devices can consume a huge portion of the dirty writeback cache and writeback can take a considerable time. To be able to give stricter limits, I'm proposing the following changes: 1) introduce strictlimit knob Currently the max_ratio knob exists to limit the dirty_memory. However this knob only applies once (dirty_ratio + dirty_background_ratio) / 2 has been reached. With the BDI_CAP_STRICTLIMIT flag, the max_ratio can be applied without reaching that limit. This change exposes that knob. This knob can also be useful for NFS, fuse filesystems and USB devices. 2) Use part of 1000000 internal calculation The max_ratio is based on percentage. With the current machine sizes percentage values can be very high (1% of a 256GB main memory is already 2.5GB). This change uses part of 1000000 instead of percentages for the internal calculations. 3) Introduce two new sysfs knobs: min_bytes and max_bytes. Currently all calculations are based on ratio, but for a user it often more convenient to specify a limit in bytes. The new knobs will not store bytes values, instead they will translate the byte value to a corresponding ratio. As the internal values are now part of 1000, the ratio is closer to the specified value. However the value should be more seen as an approximation as it can fluctuate over time. 3) Introduce two new sysfs knobs: min_ratio_fine and max_ratio_fine. The granularity for the existing sysfs bdi knobs min_ratio and max_ratio is based on percentage values. The new sysfs bdi knobs min_ratio_fine and max_ratio_fine allow to specify the ratio as part of 1 million. This patch (of 20): This adds the bdi_set_strict_limit function to be able to set/unset the BDI_CAP_STRICTLIMIT flag. Link: https://lkml.kernel.org/r/20221119005215.3052436-1-shr@devkernel.io Link: https://lkml.kernel.org/r/20221119005215.3052436-2-shr@devkernel.io Signed-off-by: Stefan Roesch Cc: Jens Axboe Cc: Chris Mason Signed-off-by: Andrew Morton