File 0003-btrfs-progs-add-helpers-for-parsing-filesy... of Package btrfsprogs

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File 0003-btrfs-progs-add-helpers-for-parsing-filesystem-exclu.patch of Package btrfsprogs

From 639ddf61ca6dc0008a18ca63f05bccf6e5837bbe Mon Sep 17 00:00:00 2001
From: David Sterba <dsterba@suse.com>
Date: Thu, 5 Nov 2020 01:06:29 +0100
Subject: [PATCH] btrfs-progs: add helpers for parsing filesystem exclusive
 operation

Since kernel 5.10, the file /sys/fs/btrfs/FSID/exclusive_operation
exports textual id of the running exclusive operation (balance, device
add/remove, ...). Add definitions and parsing functions so they can be
used to check before another operation is started and potentially
blocks.

Signed-off-by: David Sterba <dsterba@suse.com>

---
 utils.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 utils.h |   13 +++++++++++++
 2 files changed, 63 insertions(+)

--- a/utils.c
+++ b/utils.c
@@ -2631,3 +2631,53 @@
 	memset(buf, 0, size);
 	return read(fd, buf, size);
 }
+
+static const char exclop_def[][16] = {
+	[BTRFS_EXCLOP_NONE]		"none",
+	[BTRFS_EXCLOP_BALANCE]		"balance",
+	[BTRFS_EXCLOP_DEV_ADD]		"device add",
+	[BTRFS_EXCLOP_DEV_REMOVE]	"device remove",
+	[BTRFS_EXCLOP_DEV_REPLACE]	"device replace",
+	[BTRFS_EXCLOP_RESIZE]		"resize",
+	[BTRFS_EXCLOP_SWAP_ACTIVATE]	"swap activate",
+};
+
+/*
+ * Read currently running exclusive operation from sysfs. If this is not
+ * available, return BTRFS_EXCLOP_UNKNOWN
+ */
+int get_fs_exclop(int fd)
+{
+	int sysfs_fd;
+	char buf[32];
+	int ret;
+	int i;
+
+	sysfs_fd = sysfs_open_fsid_file(fd, "exclusive_operation");
+	if (sysfs_fd < 0)
+		return BTRFS_EXCLOP_UNKNOWN;
+
+	memset(buf, 0, sizeof(buf));
+	ret = sysfs_read_file(sysfs_fd, buf, sizeof(buf));
+	close(sysfs_fd);
+	if (ret <= 0)
+		return BTRFS_EXCLOP_UNKNOWN;
+
+	i = strlen(buf) - 1;
+	while (i > 0 && isspace(buf[i])) i--;
+	if (i > 0)
+		buf[i + 1] = 0;
+	for (i = 0; i < ARRAY_SIZE(exclop_def); i++) {
+		if (strcmp(exclop_def[i], buf) == 0)
+			return i;
+	}
+
+	return BTRFS_EXCLOP_UNKNOWN;
+}
+
+const char *get_fs_exclop_name(int op)
+{
+	if (0 <= op && op <= ARRAY_SIZE(exclop_def))
+		return exclop_def[op];
+	return "UNKNOWN";
+}
--- a/utils.h
+++ b/utils.h
@@ -63,6 +63,17 @@
 #define UNITS_HUMAN			(UNITS_HUMAN_BINARY)
 #define UNITS_DEFAULT			(UNITS_HUMAN)
 
+enum exclusive_operation {
+	BTRFS_EXCLOP_NONE,
+	BTRFS_EXCLOP_BALANCE,
+	BTRFS_EXCLOP_DEV_ADD,
+	BTRFS_EXCLOP_DEV_REMOVE,
+	BTRFS_EXCLOP_DEV_REPLACE,
+	BTRFS_EXCLOP_RESIZE,
+	BTRFS_EXCLOP_SWAP_ACTIVATE,
+	BTRFS_EXCLOP_UNKNOWN = -1,
+};
+
 void units_set_mode(unsigned *units, unsigned mode);
 void units_set_base(unsigned *units, unsigned base);
 
@@ -112,6 +123,8 @@
 		struct btrfs_ioctl_dev_info_args **di_ret);
 int get_fsid(const char *path, u8 *fsid, int silent);
 int get_fsid_fd(int fd, u8 *fsid);
+int get_fs_exclop(int fd);
+const char *get_fs_exclop_name(int op);
 
 int is_seen_fsid(u8 *fsid, struct seen_fsid *seen_fsid_hash[]);
 int add_seen_fsid(u8 *fsid, struct seen_fsid *seen_fsid_hash[],

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