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https://github.com/torvalds/linux
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b7625f461d
[BUG] Since the introduction of per-fs feature sysfs interface (/sys/fs/btrfs/<UUID>/features/), the content of that directory is never updated. Thus for the following case, that directory will not show the new features like RAID56: # mkfs.btrfs -f $dev1 $dev2 $dev3 # mount $dev1 $mnt # btrfs balance start -f -mconvert=raid5 $mnt # ls /sys/fs/btrfs/$uuid/features/ extended_iref free_space_tree no_holes skinny_metadata While after unmount and mount, we got the correct features: # umount $mnt # mount $dev1 $mnt # ls /sys/fs/btrfs/$uuid/features/ extended_iref free_space_tree no_holes raid56 skinny_metadata [CAUSE] Because we never really try to update the content of per-fs features/ directory. We had an attempt to update the features directory dynamically in commit14e46e0495("btrfs: synchronize incompat feature bits with sysfs files"), but unfortunately it get reverted in commite410e34fad("Revert "btrfs: synchronize incompat feature bits with sysfs files""). The problem in the original patch is, in the context of btrfs_create_chunk(), we can not afford to update the sysfs group. The exported but never utilized function, btrfs_sysfs_feature_update() is the leftover of such attempt. As even if we go sysfs_update_group(), new files will need extra memory allocation, and we have no way to specify the sysfs update to go GFP_NOFS. [FIX] This patch will address the old problem by doing asynchronous sysfs update in the cleaner thread. This involves the following changes: - Make __btrfs_(set|clear)_fs_(incompat|compat_ro) helpers to set BTRFS_FS_FEATURE_CHANGED flag when needed - Update btrfs_sysfs_feature_update() to use sysfs_update_group() And drop unnecessary arguments. - Call btrfs_sysfs_feature_update() in cleaner_kthread If we have the BTRFS_FS_FEATURE_CHANGED flag set. - Wake up cleaner_kthread in btrfs_commit_transaction if we have BTRFS_FS_FEATURE_CHANGED flag By this, all the previously dangerous call sites like btrfs_create_chunk() need no new changes, as above helpers would have already set the BTRFS_FS_FEATURE_CHANGED flag. The real work happens at cleaner_kthread, thus we pay the cost of delaying the update to sysfs directory, but the delayed time should be small enough that end user can not distinguish though it might get delayed if the cleaner thread is busy with removing subvolumes or defrag. CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "messages.h"
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#include "ctree.h"
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#include "fs.h"
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#include "accessors.h"
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void __btrfs_set_fs_incompat(struct btrfs_fs_info *fs_info, u64 flag,
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const char *name)
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{
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struct btrfs_super_block *disk_super;
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u64 features;
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disk_super = fs_info->super_copy;
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features = btrfs_super_incompat_flags(disk_super);
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if (!(features & flag)) {
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spin_lock(&fs_info->super_lock);
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features = btrfs_super_incompat_flags(disk_super);
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if (!(features & flag)) {
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features |= flag;
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btrfs_set_super_incompat_flags(disk_super, features);
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btrfs_info(fs_info,
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"setting incompat feature flag for %s (0x%llx)",
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name, flag);
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}
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spin_unlock(&fs_info->super_lock);
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set_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags);
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}
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}
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void __btrfs_clear_fs_incompat(struct btrfs_fs_info *fs_info, u64 flag,
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const char *name)
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{
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struct btrfs_super_block *disk_super;
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u64 features;
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disk_super = fs_info->super_copy;
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features = btrfs_super_incompat_flags(disk_super);
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if (features & flag) {
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spin_lock(&fs_info->super_lock);
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features = btrfs_super_incompat_flags(disk_super);
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if (features & flag) {
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features &= ~flag;
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btrfs_set_super_incompat_flags(disk_super, features);
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btrfs_info(fs_info,
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"clearing incompat feature flag for %s (0x%llx)",
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name, flag);
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}
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spin_unlock(&fs_info->super_lock);
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set_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags);
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}
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}
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void __btrfs_set_fs_compat_ro(struct btrfs_fs_info *fs_info, u64 flag,
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const char *name)
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{
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struct btrfs_super_block *disk_super;
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u64 features;
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disk_super = fs_info->super_copy;
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features = btrfs_super_compat_ro_flags(disk_super);
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if (!(features & flag)) {
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spin_lock(&fs_info->super_lock);
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features = btrfs_super_compat_ro_flags(disk_super);
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if (!(features & flag)) {
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features |= flag;
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btrfs_set_super_compat_ro_flags(disk_super, features);
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btrfs_info(fs_info,
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"setting compat-ro feature flag for %s (0x%llx)",
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name, flag);
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}
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spin_unlock(&fs_info->super_lock);
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set_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags);
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}
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}
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void __btrfs_clear_fs_compat_ro(struct btrfs_fs_info *fs_info, u64 flag,
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const char *name)
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{
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struct btrfs_super_block *disk_super;
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u64 features;
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disk_super = fs_info->super_copy;
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features = btrfs_super_compat_ro_flags(disk_super);
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if (features & flag) {
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spin_lock(&fs_info->super_lock);
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features = btrfs_super_compat_ro_flags(disk_super);
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if (features & flag) {
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features &= ~flag;
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btrfs_set_super_compat_ro_flags(disk_super, features);
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btrfs_info(fs_info,
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"clearing compat-ro feature flag for %s (0x%llx)",
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name, flag);
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}
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spin_unlock(&fs_info->super_lock);
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set_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags);
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}
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}
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