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btrfs-util: add helper that abstracts "might be btrfs subvol?" check

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Let#s not hardcode inode nr 256 everywhere, but abstract this check
slightly.
This commit is contained in:
Lennart Poettering 2021-02-26 17:39:55 +01:00 committed by Yu Watanabe
parent 35f4b6d8ba
commit 674b04ff1b
5 changed files with 16 additions and 7 deletions
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6
src/basic/btrfs-util.c
View File

@ -91,7 +91,7 @@ int btrfs_is_subvol_fd(int fd) {
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode) || st.st_ino != 256)
if (!btrfs_might_be_subvol(&st))
return 0;
return btrfs_is_filesystem(fd);
@ -194,7 +194,7 @@ int btrfs_subvol_set_read_only_fd(int fd, bool b) {
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode) || st.st_ino != 256)
if (!btrfs_might_be_subvol(&st))
return -EINVAL;
if (ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags) < 0)
@ -229,7 +229,7 @@ int btrfs_subvol_get_read_only_fd(int fd) {
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISDIR(st.st_mode) || st.st_ino != 256)
if (!btrfs_might_be_subvol(&st))
return -EINVAL;
if (ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags) < 0)

10
src/basic/btrfs-util.h
View File

@ -127,3 +127,13 @@ static inline int btrfs_log_dev_root(int level, int ret, const char *p) {
"File system behind %s is reported by btrfs to be backed by pseudo-device /dev/root, which is not a valid userspace accessible device node. "
"Cannot determine correct backing block device.", p);
}
static inline bool btrfs_might_be_subvol(const struct stat *st) {
if (!st)
return false;
/* Returns true if this 'struct stat' looks like it could refer to a btrfs subvolume. To make a final
* decision, needs to be combined with an fstatfs() check to see if this is actually btrfs. */
return S_ISDIR(st->st_mode) && st->st_ino == 256;
}

2
src/basic/rm-rf.c
View File

@ -147,7 +147,7 @@ int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
if (r > 0)
continue;
if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
/* This could be a subvolume, try to remove it */

2
src/import/export-tar.c
View File

@ -283,7 +283,7 @@ int tar_export_start(TarExport *e, const char *path, int fd, ImportCompressType
e->quota_referenced = (uint64_t) -1;
if (e->st.st_ino == 256) { /* might be a btrfs subvolume? */
if (btrfs_might_be_subvol(&e->st)) {
BtrfsQuotaInfo q;
r = btrfs_subvol_get_subtree_quota_fd(sfd, 0, &q);

3
src/shared/discover-image.c
View File

@ -260,8 +260,7 @@ static int image_make(
if (fd < 0)
return -errno;
/* btrfs subvolumes have inode 256 */
if (st->st_ino == 256) {
if (btrfs_might_be_subvol(st)) {
r = btrfs_is_filesystem(fd);
if (r < 0)