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From: David Sterba <dsterba@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: David Sterba <dsterba@suse.com>
Subject: [PATCH 4/6] btrfs: add wrapper for conditional start of exclusive operation
Date: Fri, 21 May 2021 14:06:34 +0200	[thread overview]
Message-ID: <fe9738eb5db055e06eafb178bf6aea41c48b2890.1621526221.git.dsterba@suse.com> (raw)
In-Reply-To: <cover.1621526221.git.dsterba@suse.com>

To support optional cancelation of some operations, add helper that will
wrap all the combinations. In normal mode it's same as
btrfs_exclop_start, in cancelation mode it checks if it's already
running and request cancelation and waits until completion.

The error codes can be returned to to user space and semantics is not
changed, adding ECANCELED. This should be evaluated as an error and that
the operation has not completed and the operation should be restarted
or the filesystem status reviewed.

Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/ioctl.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index cacd6ee17d8e..c75ccadf23dc 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1600,6 +1600,48 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 	return ret;
 }
 
+/*
+ * Try to start exclusive operation @type or cancel it if it's running.
+ *
+ * Return:
+ *   0        - normal mode, newly claimed op started
+ *  >0        - normal mode, something else is running,
+ *              return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS to user space
+ * ECANCELED  - cancel mode, successful cancel
+ * ENOTCONN   - cancel mode, operation not running anymore
+ */
+static int exclop_start_or_cancel_reloc(struct btrfs_fs_info *fs_info,
+			enum btrfs_exclusive_operation type, bool cancel)
+{
+	if (!cancel) {
+		/* Start normal op */
+		if (!btrfs_exclop_start(fs_info, type))
+			return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
+		/* Exclusive operation is now claimed */
+		return 0;
+	}
+
+	/* Cancel running op */
+	if (btrfs_exclop_start_try_lock(fs_info, type)) {
+		/*
+		 * This blocks any exclop finish from setting it to NONE, so we
+		 * request cancelation. Either it runs and we will wait for it,
+		 * or it has finished and no waiting will happen.
+		 */
+		atomic_inc(&fs_info->reloc_cancel_req);
+		btrfs_exclop_start_unlock(fs_info);
+
+		if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
+			wait_on_bit(&fs_info->flags, BTRFS_FS_RELOC_RUNNING,
+				    TASK_INTERRUPTIBLE);
+
+		return -ECANCELED;
+	}
+
+	/* Something else is running or none */
+	return -ENOTCONN;
+}
+
 static noinline int btrfs_ioctl_resize(struct file *file,
 					void __user *arg)
 {
-- 
2.29.2


  parent reply	other threads:[~2021-05-21 12:09 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-21 12:06 [PATCH 0/6] Support resize and device delete cancel ops David Sterba
2021-05-21 12:06 ` [PATCH 1/6] btrfs: protect exclusive_operation by super_lock David Sterba
2021-05-21 13:37   ` Josef Bacik
2021-05-21 12:06 ` [PATCH 2/6] btrfs: add cancelable chunk relocation support David Sterba
2021-05-21 13:21   ` Josef Bacik
2021-05-26 22:56     ` David Sterba
2021-06-16 13:54   ` Filipe Manana
2021-06-16 13:55     ` Filipe Manana
2021-06-16 15:53       ` David Sterba
2021-06-16 15:58       ` [PATCH v2] btrfs: add cancellable " David Sterba
2021-06-17  9:18         ` Filipe Manana
2021-05-21 12:06 ` [PATCH 3/6] btrfs: introduce try-lock semantics for exclusive op start David Sterba
2021-05-21 13:38   ` Josef Bacik
2021-05-27  7:43   ` Anand Jain
2021-05-28 12:30     ` David Sterba
2021-05-29 13:48       ` Anand Jain
2021-05-31 18:23         ` David Sterba
2021-05-21 12:06 ` David Sterba [this message]
2021-05-21 13:29   ` [PATCH 4/6] btrfs: add wrapper for conditional start of exclusive operation Josef Bacik
2021-05-21 16:45     ` David Sterba
2021-05-26 22:24       ` David Sterba
2021-05-21 12:06 ` [PATCH 5/6] btrfs: add cancelation to resize David Sterba
2021-05-21 13:38   ` Josef Bacik
2021-05-21 12:06 ` [PATCH 6/6] btrfs: add device delete cancel David Sterba
2021-05-21 13:38   ` Josef Bacik
2021-05-21 12:06 ` [PATCH 1/2] btrfs-progs: device remove: add support for cancel David Sterba
2021-05-21 12:06 ` [PATCH 2/2] btrfs-progs: fi resize: " David Sterba
2021-12-14 14:49 ` [PATCH 0/6] Support resize and device delete cancel ops Anand Jain
2021-12-15 15:13   ` David Sterba

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