[f2fs-dev] [PATCH RESEND] f2fs_io: add get_read_extents command for read extent cache ioctl

From: Yongpeng Yang <[email protected]>

Add support for F2FS_IOC_GET_READ_CACHE_EXTENTS ioctl which exports
the read extent cache of a file to userspace. Uses a two-call pattern:
first queries node_count, then fetches all extents.

Signed-off-by: Yongpeng Yang <[email protected]>
---
 tools/f2fs_io/f2fs_io.c | 73 +++++++++++++++++++++++++++++++++++++++++
 tools/f2fs_io/f2fs_io.h | 20 +++++++++++
 2 files changed, 93 insertions(+)

diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
index 94e61b8..3084dda 100644
--- a/tools/f2fs_io/f2fs_io.c
+++ b/tools/f2fs_io/f2fs_io.c
@@ -1948,6 +1948,78 @@ static void do_precache_extents(int argc, char **argv, const struct cmd_desc *cm
 	exit(0);
 }
 
+#define get_read_extents_desc "get read extent cache entries"
+#define get_read_extents_help					\
+"f2fs_io get_read_extents [file_path]\n\n"			\
+"  file_path : path to the target file\n"
+
+static void do_get_read_extents(int argc, char **argv,
+				const struct cmd_desc *cmd)
+{
+	struct f2fs_read_cache_extent *rec;
+	unsigned int i, count;
+	size_t alloc_size;
+	int fd, ret;
+
+	if (argc != 2) {
+		fputs("Excess arguments\n\n", stderr);
+		fputs(cmd->cmd_help, stderr);
+		exit(1);
+	}
+
+	fd = xopen(argv[1], O_RDONLY, 0);
+
+	/* first call: ext_count=0 to query the actual count */
+	alloc_size = sizeof(struct f2fs_read_cache_extent);
+	rec = xmalloc(alloc_size);
+	memset(rec, 0, alloc_size);
+
+	ret = ioctl(fd, F2FS_IOC_GET_READ_CACHE_EXTENTS, rec);
+	if (ret < 0)
+		die_errno("F2FS_IOC_GET_READ_CACHE_EXTENTS (query) failed");
+
+	count = rec->node_count;
+	printf("flags: 0x%x", rec->flags);
+	if (rec->flags & F2FS_EXT_FL_NO_EXTENT)
+		printf(" (NO_EXTENT: extent cache disabled)");
+	printf("\n");
+	printf("largest extent: fofs=%u blk=%u len=%u access_mode=%u\n",
+		rec->largest.fofs, rec->largest.blk, rec->largest.len,
+		rec->largest.last_access_mode);
+	printf("extent node count: %u\n", count);
+
+	if ((rec->flags & F2FS_EXT_FL_NO_EXTENT) || count == 0) {
+		free(rec);
+		close(fd);
+		exit(0);
+	}
+	free(rec);
+
+	/* second call: allocate array and fetch all extents */
+	alloc_size = sizeof(struct f2fs_read_cache_extent) +
+			count * sizeof(struct f2fs_cache_extent_info);
+	rec = xmalloc(alloc_size);
+	memset(rec, 0, alloc_size);
+	rec->ext_count = count;
+
+	ret = ioctl(fd, F2FS_IOC_GET_READ_CACHE_EXTENTS, rec);
+	if (ret < 0)
+		die_errno("F2FS_IOC_GET_READ_CACHE_EXTENTS (fetch) failed");
+
+	printf("\t%-12s%-12s%-12s%-12s\n", "fofs", "blk", "len", "access_mode");
+	for (i = 0; i < rec->ext_count && i < count; i++) {
+		printf("%u\t%-12u%-12u%-12u%-12u\n", i,
+			rec->extents[i].fofs,
+			rec->extents[i].blk,
+			rec->extents[i].len,
+			rec->extents[i].last_access_mode);
+	}
+
+	free(rec);
+	close(fd);
+	exit(0);
+}
+
 #define move_range_desc "moving a range of data blocks from source file to destination file"
 #define move_range_help						\
 "f2fs_io move_range [src_path] [dst_path] [src_start] [dst_start] "	\
@@ -2650,6 +2722,7 @@ const struct cmd_desc cmd_list[] = {
 	CMD(gc),
 	CMD(checkpoint),
 	CMD(precache_extents),
+	CMD(get_read_extents),
 	CMD(move_range),
 	CMD(gc_range),
 	CMD(listxattr),
diff --git a/tools/f2fs_io/f2fs_io.h b/tools/f2fs_io/f2fs_io.h
index 539964f..a84a299 100644
--- a/tools/f2fs_io/f2fs_io.h
+++ b/tools/f2fs_io/f2fs_io.h
@@ -96,6 +96,8 @@ typedef u32	__be32;
 #define F2FS_IOC_START_ATOMIC_REPLACE	_IO(F2FS_IOCTL_MAGIC, 25)
 #define F2FS_IOC_GET_DEV_ALIAS_FILE	_IOR(F2FS_IOCTL_MAGIC, 26, __u32)
 #define F2FS_IOC_IO_PRIO		_IOW(F2FS_IOCTL_MAGIC, 27, __u32)
+#define F2FS_IOC_GET_READ_CACHE_EXTENTS	_IOWR(F2FS_IOCTL_MAGIC, 28,	\
+						struct f2fs_read_cache_extent)
 
 #ifndef FSCRYPT_POLICY_V1
 #define FSCRYPT_POLICY_V1		0
@@ -263,3 +265,21 @@ struct f2fs_comp_option {
 	u8 algorithm;
 	u8 log_cluster_size;
 };
+
+struct f2fs_cache_extent_info {
+	u32 fofs;		/* start file offset in blocks */
+	u32 blk;		/* start block address */
+	u32 len;		/* length in blocks */
+	u32 last_access_mode;	/* last access mode of extent_node */
+};
+
+#define F2FS_EXT_FL_NO_EXTENT	0x1
+
+struct f2fs_read_cache_extent {
+	u32 ext_count;		/* in: array capacity; out: mapped extent count */
+	u32 flags;		/* out: status flags */
+	u32 node_count;		/* out: total extent nodes in tree */
+	u32 reserved;
+	struct f2fs_cache_extent_info largest;		/* out: largest extent */
+	struct f2fs_cache_extent_info extents[];	/* out: extent array */
+};
-- 
2.43.0



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