add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/fs/fuse/control.c
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@@ -10,6 +10,7 @@
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 #include <linux/init.h>
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 #include <linux/module.h>
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+#include <linux/fs_context.h>
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 #define FUSE_CTL_SUPER_MAGIC 0x65735543
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..
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@@ -35,7 +36,9 @@
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 {
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 	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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 	if (fc) {
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-		fuse_abort_conn(fc, true);
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+		if (fc->abort_err)
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+			fc->aborted = true;
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+		fuse_abort_conn(fc);
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 		fuse_conn_put(fc);
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 	}
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 	return count;
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@@ -117,7 +120,7 @@
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 					      const char __user *buf,
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 					      size_t count, loff_t *ppos)
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 {
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-	unsigned uninitialized_var(val);
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+	unsigned val;
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 	ssize_t ret;
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 	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
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@@ -125,7 +128,12 @@
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 	if (ret > 0) {
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 		struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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 		if (fc) {
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+			spin_lock(&fc->bg_lock);
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 			fc->max_background = val;
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+			fc->blocked = fc->num_background >= fc->max_background;
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+			if (!fc->blocked)
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+				wake_up(&fc->blocked_waitq);
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+			spin_unlock(&fc->bg_lock);
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 			fuse_conn_put(fc);
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 		}
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 	}
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@@ -154,19 +162,42 @@
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 						    const char __user *buf,
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 						    size_t count, loff_t *ppos)
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 {
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-	unsigned uninitialized_var(val);
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+	unsigned val;
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+	struct fuse_conn *fc;
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+	struct fuse_mount *fm;
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 	ssize_t ret;
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 	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
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 				    max_user_congthresh);
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-	if (ret > 0) {
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-		struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
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-		if (fc) {
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-			fc->congestion_threshold = val;
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-			fuse_conn_put(fc);
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+	if (ret <= 0)
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+		goto out;
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+	fc = fuse_ctl_file_conn_get(file);
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+	if (!fc)
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+		goto out;
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+
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+	down_read(&fc->killsb);
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+	spin_lock(&fc->bg_lock);
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+	fc->congestion_threshold = val;
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+
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+	/*
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+	 * Get any fuse_mount belonging to this fuse_conn; s_bdi is
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+	 * shared between all of them
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+	 */
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+
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+	if (!list_empty(&fc->mounts)) {
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+		fm = list_first_entry(&fc->mounts, struct fuse_mount, fc_entry);
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+		if (fc->num_background < fc->congestion_threshold) {
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+			clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC);
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+			clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC);
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+		} else {
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+			set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC);
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+			set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC);
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 		}
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 	}
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-
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+	spin_unlock(&fc->bg_lock);
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+	up_read(&fc->killsb);
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+	fuse_conn_put(fc);
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+out:
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 	return ret;
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 }
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@@ -244,7 +275,7 @@
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 	struct dentry *parent;
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 	char name[32];
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-	if (!fuse_control_sb)
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+	if (!fuse_control_sb || fc->no_control)
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 		return 0;
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 	parent = fuse_control_sb->s_root;
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@@ -282,7 +313,7 @@
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 {
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 	int i;
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-	if (!fuse_control_sb)
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+	if (!fuse_control_sb || fc->no_control)
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 		return;
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 	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
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@@ -297,7 +328,7 @@
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 	drop_nlink(d_inode(fuse_control_sb->s_root));
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 }
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-static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
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+static int fuse_ctl_fill_super(struct super_block *sb, struct fs_context *fctx)
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 {
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 	static const struct tree_descr empty_descr = {""};
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 	struct fuse_conn *fc;
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@@ -323,10 +354,19 @@
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 	return 0;
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 }
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-static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
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-			int flags, const char *dev_name, void *raw_data)
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+static int fuse_ctl_get_tree(struct fs_context *fc)
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 {
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-	return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
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+	return get_tree_single(fc, fuse_ctl_fill_super);
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+}
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+
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+static const struct fs_context_operations fuse_ctl_context_ops = {
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+	.get_tree	= fuse_ctl_get_tree,
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+};
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+
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+static int fuse_ctl_init_fs_context(struct fs_context *fc)
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+{
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+	fc->ops = &fuse_ctl_context_ops;
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+	return 0;
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 }
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 static void fuse_ctl_kill_sb(struct super_block *sb)
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@@ -345,7 +385,7 @@
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 static struct file_system_type fuse_ctl_fs_type = {
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 	.owner		= THIS_MODULE,
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 	.name		= "fusectl",
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-	.mount		= fuse_ctl_mount,
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+	.init_fs_context = fuse_ctl_init_fs_context,
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 	.kill_sb	= fuse_ctl_kill_sb,
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 };
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 MODULE_ALIAS_FS("fusectl");