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btrfsprogs/0500-btrfs-progs-get-default-subvolume.patch

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Date: Tue, 12 Jul 2011 10:48:37 +0800
From: "Zhong, Xin" <xin.zhong@intel.com>
Subject: [PATCH V3] Btrfs-progs: add "btrfs subvolume get-default" subcommand
Add subcommand to get the default subvolume of btrfs filesystem
Reviewed-by: Andreas Philipp <philipp.andreas@gmail.com>
Reviewed-by: Goffredo Baroncelli <kreijack@libero.it>
Reported-by: Yang, Yi <yi.y.yang@intel.com>
Signed-off-by: Zhong, Xin <xin.zhong@intel.com>
---
btrfs-list.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
btrfs.c | 3 ++
btrfs_cmds.c | 31 ++++++++++++++++++++++++++++-
btrfs_cmds.h | 3 +-
man/btrfs.8.in | 7 ++++++
5 files changed, 98 insertions(+), 4 deletions(-)
Index: btrfs-progs-v0.19-35-g1b444cd/btrfs-list.c
===================================================================
--- btrfs-progs-v0.19-35-g1b444cd.orig/btrfs-list.c
+++ btrfs-progs-v0.19-35-g1b444cd/btrfs-list.c
@@ -561,7 +561,7 @@ build:
return full;
}
-int list_subvols(int fd, int print_parent)
+int list_subvols(int fd, int print_parent, int get_default)
{
struct root_lookup root_lookup;
struct rb_node *n;
@@ -570,10 +570,12 @@ int list_subvols(int fd, int print_paren
struct btrfs_ioctl_search_key *sk = &args.key;
struct btrfs_ioctl_search_header *sh;
struct btrfs_root_ref *ref;
+ struct btrfs_dir_item *di;
unsigned long off = 0;
int name_len;
char *name;
u64 dir_id;
+ u64 subvol_id = 0;
int i;
int e;
@@ -670,6 +672,52 @@ int list_subvols(int fd, int print_paren
n = rb_next(n);
}
+ memset(&args, 0, sizeof(args));
+
+ /* search in the tree of tree roots */
+ sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
+
+ /* search dir item */
+ sk->max_type = BTRFS_DIR_ITEM_KEY;
+ sk->min_type = BTRFS_DIR_ITEM_KEY;
+
+ sk->max_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
+ sk->min_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
+ sk->max_offset = (u64)-1;
+ sk->max_transid = (u64)-1;
+
+ /* just a big number, doesn't matter much */
+ sk->nr_items = 4096;
+
+ /* try to get the objectid of default subvolume */
+ if (get_default) {
+ ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: can't perform the search\n");
+ return ret;
+ }
+
+ off = 0;
+ /* go through each item to find dir item named "default" */
+ for (i = 0; i < sk->nr_items; i++) {
+ sh = (struct btrfs_ioctl_search_header *)(args.buf +
+ off);
+ off += sizeof(*sh);
+ if (sh->type == BTRFS_DIR_ITEM_KEY) {
+ di = (struct btrfs_dir_item *)(args.buf + off);
+ name_len = le16_to_cpu(di->name_len);
+ name = (char *)di + sizeof(struct btrfs_dir_item);
+ if (!strncmp("default", name, name_len)) {
+ subvol_id = btrfs_disk_key_objectid(
+ &di->location);
+ break;
+ }
+ }
+
+ off += sh->len;
+ }
+ }
+
/* now that we have all the subvol-relative paths filled in,
* we have to string the subvols together so that we can get
* a path all the way back to the FS root
@@ -678,7 +726,13 @@ int list_subvols(int fd, int print_paren
while (n) {
struct root_info *entry;
entry = rb_entry(n, struct root_info, rb_node);
- resolve_root(&root_lookup, entry, print_parent);
+ if (!get_default)
+ resolve_root(&root_lookup, entry, print_parent);
+ /* we only want the default subvolume */
+ else if (subvol_id == entry->root_id)
+ resolve_root(&root_lookup, entry, print_parent);
+ else if (subvol_id == 0)
+ break;
n = rb_prev(n);
}
Index: btrfs-progs-v0.19-35-g1b444cd/btrfs.c
===================================================================
--- btrfs-progs-v0.19-35-g1b444cd.orig/btrfs.c
+++ btrfs-progs-v0.19-35-g1b444cd/btrfs.c
@@ -78,6 +78,9 @@ static struct Command commands[] = {
"as default.",
NULL
},
+ { do_get_default_subvol, 1, "subvolume get-default", "<path>\n"
+ "Get the default subvolume of a filesystem."
+ },
{ do_find_newer, 2, "subvolume find-new", "<path> <last_gen>\n"
"List the recently modified files in a filesystem.",
NULL
Index: btrfs-progs-v0.19-35-g1b444cd/btrfs_cmds.c
===================================================================
--- btrfs-progs-v0.19-35-g1b444cd.orig/btrfs_cmds.c
+++ btrfs-progs-v0.19-35-g1b444cd/btrfs_cmds.c
@@ -339,7 +339,7 @@ int do_subvol_list(int argc, char **argv
fprintf(stderr, "ERROR: can't access '%s'\n", subvol);
return 12;
}
- ret = list_subvols(fd, print_parent);
+ ret = list_subvols(fd, print_parent, 0);
if (ret)
return 19;
return 0;
@@ -991,6 +991,35 @@ int do_change_label(int nargs, char **ar
}
+int do_get_default_subvol(int nargs, char **argv)
+{
+ int fd;
+ int ret;
+ char *subvol;
+
+ subvol = argv[1];
+
+ ret = test_issubvolume(subvol);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: error accessing '%s'\n", subvol);
+ return 12;
+ }
+ if (!ret) {
+ fprintf(stderr, "ERROR: '%s' is not a subvolume\n", subvol);
+ return 13;
+ }
+
+ fd = open_file_or_dir(subvol);
+ if (fd < 0) {
+ fprintf(stderr, "ERROR: can't access '%s'\n", subvol);
+ return 12;
+ }
+ ret = list_subvols(fd, 0, 1);
+ if (ret)
+ return 19;
+ return 0;
+}
+
int do_df_filesystem(int nargs, char **argv)
{
struct btrfs_ioctl_space_args *sargs;
Index: btrfs-progs-v0.19-35-g1b444cd/btrfs_cmds.h
===================================================================
--- btrfs-progs-v0.19-35-g1b444cd.orig/btrfs_cmds.h
+++ btrfs-progs-v0.19-35-g1b444cd/btrfs_cmds.h
@@ -32,7 +32,8 @@ int do_scan(int nargs, char **argv);
int do_resize(int nargs, char **argv);
int do_subvol_list(int nargs, char **argv);
int do_set_default_subvol(int nargs, char **argv);
-int list_subvols(int fd, int print_parent);
+int do_get_default_subvol(int nargs, char **argv);
+int list_subvols(int fd, int print_parent, int get_default);
int do_df_filesystem(int nargs, char **argv);
int find_updated_files(int fd, u64 root_id, u64 oldest_gen);
int do_find_newer(int argc, char **argv);
Index: btrfs-progs-v0.19-35-g1b444cd/man/btrfs.8.in
===================================================================
--- btrfs-progs-v0.19-35-g1b444cd.orig/man/btrfs.8.in
+++ btrfs-progs-v0.19-35-g1b444cd/man/btrfs.8.in
@@ -15,6 +15,8 @@ btrfs \- control a btrfs filesystem
.PP
\fBbtrfs\fP \fBsubvolume set-default\fP\fI <id> <path>\fP
.PP
+\fBbtrfs\fP \fBsubvolume get-default\fP\fI <path>\fP
+.PP
\fBbtrfs\fP \fBfilesystem sync\fP\fI <path> \fP
.PP
\fBbtrfs\fP \fBfilesystem resize\fP\fI [+/\-]<size>[gkm]|max <filesystem>\fP
@@ -120,6 +122,11 @@ Set the subvolume of the filesystem \fI<
is returned by the \fBsubvolume list\fR command.
.TP
+\fBsubvolume get-default\fR\fI <path>\fR
+Get the default subvolume of the filesystem \fI<path>\fR. The output format
+is similar to \fBsubvolume list\fR command.
+.TP
+
\fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] [-s \fIstart\fR] [-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> [<\fIfile\fR>|<\fIdir\fR>...]
Defragment file data and/or directory metadata. To defragment all files in a
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