[4/6] fs: add owner of freeze/thaw

Message ID	20250401-work-freeze-v1-4-d000611d4ab0@kernel.org (mailing list archive)
State	New
Headers	show Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0D633B2A0; Tue, 1 Apr 2025 00:33:43 +0000 (UTC) From: Christian Brauner <brauner@kernel.org> To: linux-fsdevel@vger.kernel.org, jack@suse.cz Cc: Christian Brauner <brauner@kernel.org>, Ard Biesheuvel <ardb@kernel.org>, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, James Bottomley <James.Bottomley@hansenpartnership.com>, mcgrof@kernel.org, hch@infradead.org, david@fromorbit.com, rafael@kernel.org, djwong@kernel.org, pavel@kernel.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com Subject: [PATCH 4/6] fs: add owner of freeze/thaw Date: Tue, 1 Apr 2025 02:32:49 +0200 Message-ID: <20250401-work-freeze-v1-4-d000611d4ab0@kernel.org> In-Reply-To: <20250401-work-freeze-v1-0-d000611d4ab0@kernel.org> References: <20250401-work-freeze-v1-0-d000611d4ab0@kernel.org> Precedence: bulk MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit
Series	power: wire-up filesystem freeze/thaw with suspend/resume \| expand [0/6] power: wire-up filesystem freeze/thaw with suspend/resume [1/6] ext4: replace kthread freezing with auto fs freezing [2/6] btrfs: replace kthread freezing with auto fs freezing [3/6] xfs: replace kthread freezing with auto fs freezing [4/6] fs: add owner of freeze/thaw [5/6] fs: allow pagefault based writers to be frozen [6/6] power: freeze filesystems during suspend/resume

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 2b8f9239bede..3e8af62c9e15 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -2271,12 +2271,12 @@ int f2fs_resize_fs(struct file *filp, __u64 block_count) if (err) return err; - err = freeze_super(sbi->sb, FREEZE_HOLDER_USERSPACE); + err = freeze_super(sbi->sb, FREEZE_HOLDER_USERSPACE, NULL); if (err) return err; if (f2fs_readonly(sbi->sb)) { - err = thaw_super(sbi->sb, FREEZE_HOLDER_USERSPACE); + err = thaw_super(sbi->sb, FREEZE_HOLDER_USERSPACE, NULL); if (err) return err; return -EROFS; @@ -2333,6 +2333,6 @@ int f2fs_resize_fs(struct file *filp, __u64 block_count) out_err: f2fs_up_write(&sbi->cp_global_sem); f2fs_up_write(&sbi->gc_lock); - thaw_super(sbi->sb, FREEZE_HOLDER_USERSPACE); + thaw_super(sbi->sb, FREEZE_HOLDER_USERSPACE, NULL); return err; } diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c index 44e5658b896c..519943189109 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -674,7 +674,7 @@ static int gfs2_sync_fs(struct super_block *sb, int wait) return sdp->sd_log_error; } -static int gfs2_do_thaw(struct gfs2_sbd *sdp) +static int gfs2_do_thaw(struct gfs2_sbd *sdp, enum freeze_holder who, const void *freeze_owner) { struct super_block *sb = sdp->sd_vfs; int error; @@ -682,7 +682,7 @@ static int gfs2_do_thaw(struct gfs2_sbd *sdp) error = gfs2_freeze_lock_shared(sdp); if (error) goto fail; - error = thaw_super(sb, FREEZE_HOLDER_USERSPACE); + error = thaw_super(sb, who, freeze_owner); if (!error) return 0; @@ -703,14 +703,14 @@ void gfs2_freeze_func(struct work_struct *work) if (test_bit(SDF_FROZEN, &sdp->sd_flags)) goto freeze_failed; - error = freeze_super(sb, FREEZE_HOLDER_USERSPACE); + error = freeze_super(sb, FREEZE_HOLDER_USERSPACE, NULL); if (error) goto freeze_failed; gfs2_freeze_unlock(sdp); set_bit(SDF_FROZEN, &sdp->sd_flags); - error = gfs2_do_thaw(sdp); + error = gfs2_do_thaw(sdp, FREEZE_HOLDER_USERSPACE, NULL); if (error) goto out; @@ -731,7 +731,8 @@ void gfs2_freeze_func(struct work_struct *work) * */ -static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who) +static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who, + const void *freeze_owner) { struct gfs2_sbd *sdp = sb->s_fs_info; int error; @@ -744,7 +745,7 @@ static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who) } for (;;) { - error = freeze_super(sb, FREEZE_HOLDER_USERSPACE); + error = freeze_super(sb, who, freeze_owner); if (error) { fs_info(sdp, "GFS2: couldn't freeze filesystem: %d\n", error); @@ -758,7 +759,7 @@ static int gfs2_freeze_super(struct super_block *sb, enum freeze_holder who) break; } - error = gfs2_do_thaw(sdp); + error = gfs2_do_thaw(sdp, who, freeze_owner); if (error) goto out; @@ -799,7 +800,8 @@ static int gfs2_freeze_fs(struct super_block *sb) * */ -static int gfs2_thaw_super(struct super_block *sb, enum freeze_holder who) +static int gfs2_thaw_super(struct super_block *sb, enum freeze_holder who, + const void *freeze_owner) { struct gfs2_sbd *sdp = sb->s_fs_info; int error; @@ -814,7 +816,7 @@ static int gfs2_thaw_super(struct super_block *sb, enum freeze_holder who) atomic_inc(&sb->s_active); gfs2_freeze_unlock(sdp); - error = gfs2_do_thaw(sdp); + error = gfs2_do_thaw(sdp, who, freeze_owner); if (!error) { clear_bit(SDF_FREEZE_INITIATOR, &sdp->sd_flags); diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index ecc699f8d9fc..748125653d6c 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -174,10 +174,10 @@ static ssize_t freeze_store(struct gfs2_sbd *sdp, const char *buf, size_t len) switch (n) { case 0: - error = thaw_super(sdp->sd_vfs, FREEZE_HOLDER_USERSPACE); + error = thaw_super(sdp->sd_vfs, FREEZE_HOLDER_USERSPACE, NULL); break; case 1: - error = freeze_super(sdp->sd_vfs, FREEZE_HOLDER_USERSPACE); + error = freeze_super(sdp->sd_vfs, FREEZE_HOLDER_USERSPACE, NULL); break; default: return -EINVAL; diff --git a/fs/ioctl.c b/fs/ioctl.c index c91fd2b46a77..bedc83fc2f20 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -396,8 +396,8 @@ static int ioctl_fsfreeze(struct file *filp) /* Freeze */ if (sb->s_op->freeze_super) - return sb->s_op->freeze_super(sb, FREEZE_HOLDER_USERSPACE); - return freeze_super(sb, FREEZE_HOLDER_USERSPACE); + return sb->s_op->freeze_super(sb, FREEZE_HOLDER_USERSPACE, NULL); + return freeze_super(sb, FREEZE_HOLDER_USERSPACE, NULL); } static int ioctl_fsthaw(struct file *filp) @@ -409,8 +409,8 @@ static int ioctl_fsthaw(struct file *filp) /* Thaw */ if (sb->s_op->thaw_super) - return sb->s_op->thaw_super(sb, FREEZE_HOLDER_USERSPACE); - return thaw_super(sb, FREEZE_HOLDER_USERSPACE); + return sb->s_op->thaw_super(sb, FREEZE_HOLDER_USERSPACE, NULL); + return thaw_super(sb, FREEZE_HOLDER_USERSPACE, NULL); } static int ioctl_file_dedupe_range(struct file *file, diff --git a/fs/super.c b/fs/super.c index 3c4a496d6438..606072a3fab9 100644 --- a/fs/super.c +++ b/fs/super.c @@ -39,7 +39,8 @@ #include <uapi/linux/mount.h> #include "internal.h" -static int thaw_super_locked(struct super_block *sb, enum freeze_holder who); +static int thaw_super_locked(struct super_block *sb, enum freeze_holder who, + const void *freeze_owner); static LIST_HEAD(super_blocks); static DEFINE_SPINLOCK(sb_lock); @@ -1148,7 +1149,7 @@ static void do_thaw_all_callback(struct super_block *sb, void *unused) if (IS_ENABLED(CONFIG_BLOCK)) while (sb->s_bdev && !bdev_thaw(sb->s_bdev)) pr_warn("Emergency Thaw on %pg\n", sb->s_bdev); - thaw_super_locked(sb, FREEZE_HOLDER_USERSPACE); + thaw_super_locked(sb, FREEZE_HOLDER_USERSPACE, NULL); return; } @@ -1522,10 +1523,10 @@ static int fs_bdev_freeze(struct block_device *bdev) if (sb->s_op->freeze_super) error = sb->s_op->freeze_super(sb, - FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL); else error = freeze_super(sb, - FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL); if (!error) error = sync_blockdev(bdev); deactivate_super(sb); @@ -1571,10 +1572,10 @@ static int fs_bdev_thaw(struct block_device *bdev) if (sb->s_op->thaw_super) error = sb->s_op->thaw_super(sb, - FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL); else error = thaw_super(sb, - FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL); deactivate_super(sb); return error; } @@ -1946,7 +1947,7 @@ static int wait_for_partially_frozen(struct super_block *sb) } #define FREEZE_HOLDERS (FREEZE_HOLDER_KERNEL | FREEZE_HOLDER_USERSPACE) -#define FREEZE_FLAGS (FREEZE_HOLDERS | FREEZE_MAY_NEST) +#define FREEZE_FLAGS (FREEZE_HOLDERS | FREEZE_MAY_NEST | FREEZE_EXCL) static inline int freeze_inc(struct super_block *sb, enum freeze_holder who) { @@ -1977,6 +1978,21 @@ static inline bool may_freeze(struct super_block *sb, enum freeze_holder who) WARN_ON_ONCE((who & ~FREEZE_FLAGS)); WARN_ON_ONCE(hweight32(who & FREEZE_HOLDERS) > 1); + if (who & FREEZE_EXCL) { + if (WARN_ON_ONCE(!(who & FREEZE_HOLDER_KERNEL))) + return false; + + if (who & ~(FREEZE_EXCL | FREEZE_HOLDER_KERNEL)) + return false; + + return (sb->s_writers.freeze_kcount + + sb->s_writers.freeze_ucount) == 0; + } + + /* This filesystem is already exclusively frozen. */ + if (sb->s_writers.freeze_owner) + return false; + if (who & FREEZE_HOLDER_KERNEL) return (who & FREEZE_MAY_NEST) || sb->s_writers.freeze_kcount == 0; @@ -1986,10 +2002,30 @@ static inline bool may_freeze(struct super_block *sb, enum freeze_holder who) return false; } +static inline bool may_unfreeze(struct super_block *sb, enum freeze_holder who, + const void *freeze_owner) +{ + WARN_ON_ONCE((who & ~FREEZE_FLAGS)); + WARN_ON_ONCE(hweight32(who & FREEZE_HOLDERS) > 1); + + if (who & FREEZE_EXCL) { + if (WARN_ON_ONCE(sb->s_writers.freeze_owner == NULL)) + return false; + if (WARN_ON_ONCE(!(who & FREEZE_HOLDER_KERNEL))) + return false; + if (who & ~(FREEZE_EXCL | FREEZE_HOLDER_KERNEL)) + return false; + return sb->s_writers.freeze_owner == freeze_owner; + } + + return sb->s_writers.freeze_owner == NULL; +} + /** * freeze_super - lock the filesystem and force it into a consistent state * @sb: the super to lock * @who: context that wants to freeze + * @freeze_owner: owner of the freeze * * Syncs the super to make sure the filesystem is consistent and calls the fs's * freeze_fs. Subsequent calls to this without first thawing the fs may return @@ -2041,7 +2077,7 @@ static inline bool may_freeze(struct super_block *sb, enum freeze_holder who) * Return: If the freeze was successful zero is returned. If the freeze * failed a negative error code is returned. */ -int freeze_super(struct super_block *sb, enum freeze_holder who) +int freeze_super(struct super_block *sb, enum freeze_holder who, const void *freeze_owner) { int ret; @@ -2075,6 +2111,7 @@ int freeze_super(struct super_block *sb, enum freeze_holder who) if (sb_rdonly(sb)) { /* Nothing to do really... */ WARN_ON_ONCE(freeze_inc(sb, who) > 1); + sb->s_writers.freeze_owner = freeze_owner; sb->s_writers.frozen = SB_FREEZE_COMPLETE; wake_up_var(&sb->s_writers.frozen); super_unlock_excl(sb); @@ -2122,6 +2159,7 @@ int freeze_super(struct super_block *sb, enum freeze_holder who) * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super(). */ WARN_ON_ONCE(freeze_inc(sb, who) > 1); + sb->s_writers.freeze_owner = freeze_owner; sb->s_writers.frozen = SB_FREEZE_COMPLETE; wake_up_var(&sb->s_writers.frozen); lockdep_sb_freeze_release(sb); @@ -2136,13 +2174,17 @@ EXPORT_SYMBOL(freeze_super); * removes that state without releasing the other state or unlocking the * filesystem. */ -static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) +static int thaw_super_locked(struct super_block *sb, enum freeze_holder who, + const void *freeze_owner) { int error = -EINVAL; if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) goto out_unlock; + if (!may_unfreeze(sb, who, freeze_owner)) + goto out_unlock; + /* * All freezers share a single active reference. * So just unlock in case there are any left. @@ -2152,6 +2194,7 @@ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) if (sb_rdonly(sb)) { sb->s_writers.frozen = SB_UNFROZEN; + sb->s_writers.freeze_owner = NULL; wake_up_var(&sb->s_writers.frozen); goto out_deactivate; } @@ -2169,6 +2212,7 @@ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) } sb->s_writers.frozen = SB_UNFROZEN; + sb->s_writers.freeze_owner = NULL; wake_up_var(&sb->s_writers.frozen); sb_freeze_unlock(sb, SB_FREEZE_FS); out_deactivate: @@ -2184,6 +2228,7 @@ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) * thaw_super -- unlock filesystem * @sb: the super to thaw * @who: context that wants to freeze + * @freeze_owner: owner of the freeze * * Unlocks the filesystem and marks it writeable again after freeze_super() * if there are no remaining freezes on the filesystem. @@ -2197,13 +2242,14 @@ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) * have been frozen through the block layer via multiple block devices. * The filesystem remains frozen until all block devices are unfrozen. */ -int thaw_super(struct super_block *sb, enum freeze_holder who) +int thaw_super(struct super_block *sb, enum freeze_holder who, + const void *freeze_owner) { if (!super_lock_excl(sb)) { WARN_ON_ONCE("Dying superblock while thawing!"); return -EINVAL; } - return thaw_super_locked(sb, who); + return thaw_super_locked(sb, who, freeze_owner); } EXPORT_SYMBOL(thaw_super); diff --git a/fs/xfs/scrub/fscounters.c b/fs/xfs/scrub/fscounters.c index e629663e460a..9b598c5790ad 100644 --- a/fs/xfs/scrub/fscounters.c +++ b/fs/xfs/scrub/fscounters.c @@ -123,7 +123,7 @@ xchk_fsfreeze( { int error; - error = freeze_super(sc->mp->m_super, FREEZE_HOLDER_KERNEL); + error = freeze_super(sc->mp->m_super, FREEZE_HOLDER_KERNEL, NULL); trace_xchk_fsfreeze(sc, error); return error; } @@ -135,7 +135,7 @@ xchk_fsthaw( int error; /* This should always succeed, we have a kernel freeze */ - error = thaw_super(sc->mp->m_super, FREEZE_HOLDER_KERNEL); + error = thaw_super(sc->mp->m_super, FREEZE_HOLDER_KERNEL, NULL); trace_xchk_fsthaw(sc, error); return error; } diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c index ed8d8ed42f0a..3545dc1d953c 100644 --- a/fs/xfs/xfs_notify_failure.c +++ b/fs/xfs/xfs_notify_failure.c @@ -127,7 +127,7 @@ xfs_dax_notify_failure_freeze( struct super_block *sb = mp->m_super; int error; - error = freeze_super(sb, FREEZE_HOLDER_KERNEL); + error = freeze_super(sb, FREEZE_HOLDER_KERNEL, NULL); if (error) xfs_emerg(mp, "already frozen by kernel, err=%d", error); @@ -143,7 +143,7 @@ xfs_dax_notify_failure_thaw( int error; if (kernel_frozen) { - error = thaw_super(sb, FREEZE_HOLDER_KERNEL); + error = thaw_super(sb, FREEZE_HOLDER_KERNEL, NULL); if (error) xfs_emerg(mp, "still frozen after notify failure, err=%d", error); @@ -153,7 +153,7 @@ xfs_dax_notify_failure_thaw( * Also thaw userspace call anyway because the device is about to be * removed immediately. */ - thaw_super(sb, FREEZE_HOLDER_USERSPACE); + thaw_super(sb, FREEZE_HOLDER_USERSPACE, NULL); } static int diff --git a/include/linux/fs.h b/include/linux/fs.h index 1aa578412f1b..b379a46b5576 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1307,6 +1307,7 @@ struct sb_writers { unsigned short frozen; /* Is sb frozen? */ int freeze_kcount; /* How many kernel freeze requests? */ int freeze_ucount; /* How many userspace freeze requests? */ + const void *freeze_owner; /* Owner of the freeze */ struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS]; }; @@ -2270,6 +2271,7 @@ extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos, * @FREEZE_HOLDER_KERNEL: kernel wants to freeze or thaw filesystem * @FREEZE_HOLDER_USERSPACE: userspace wants to freeze or thaw filesystem * @FREEZE_MAY_NEST: whether nesting freeze and thaw requests is allowed + * @FREEZE_EXCL: whether actual freezing must be done by the caller * * Indicate who the owner of the freeze or thaw request is and whether * the freeze needs to be exclusive or can nest. @@ -2283,6 +2285,7 @@ enum freeze_holder { FREEZE_HOLDER_KERNEL = (1U << 0), FREEZE_HOLDER_USERSPACE = (1U << 1), FREEZE_MAY_NEST = (1U << 2), + FREEZE_EXCL = (1U << 3), }; struct super_operations { @@ -2296,9 +2299,9 @@ struct super_operations { void (*evict_inode) (struct inode *); void (*put_super) (struct super_block *); int (*sync_fs)(struct super_block *sb, int wait); - int (*freeze_super) (struct super_block *, enum freeze_holder who); + int (*freeze_super) (struct super_block *, enum freeze_holder who, const void *owner); int (*freeze_fs) (struct super_block *); - int (*thaw_super) (struct super_block *, enum freeze_holder who); + int (*thaw_super) (struct super_block *, enum freeze_holder who, const void *owner); int (*unfreeze_fs) (struct super_block *); int (*statfs) (struct dentry *, struct kstatfs *); int (*remount_fs) (struct super_block *, int *, char *); @@ -2706,8 +2709,10 @@ extern int unregister_filesystem(struct file_system_type *); extern int vfs_statfs(const struct path *, struct kstatfs *); extern int user_statfs(const char __user *, struct kstatfs *); extern int fd_statfs(int, struct kstatfs *); -int freeze_super(struct super_block *super, enum freeze_holder who); -int thaw_super(struct super_block *super, enum freeze_holder who); +int freeze_super(struct super_block *super, enum freeze_holder who, + const void *freeze_owner); +int thaw_super(struct super_block *super, enum freeze_holder who, + const void *freeze_owner); extern __printf(2, 3) int super_setup_bdi_name(struct super_block *sb, char *fmt, ...); extern int super_setup_bdi(struct super_block *sb);

[4/6] fs: add owner of freeze/thaw

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