shared/copy: add a new flag COPY_ALL_XATTRS

When the flag COPY_ALL_XATTRS is set, it causes the complete set of xattrs
to be copied. If the flag is unset, only xattrs from the "user" namespace
are copied.

Fixes #17178.

src/shared/btrfs-util.c

@@ -1628,6 +1628,7 @@ int btrfs_subvol_snapshot_fd_full(
                                 COPY_REFLINK|
                                 COPY_SAME_MOUNT|
                                 COPY_HARDLINKS|
+                                COPY_ALL_XATTRS|
                                 (FLAGS_SET(flags, BTRFS_SNAPSHOT_SIGINT) ? COPY_SIGINT : 0)|
                                 (FLAGS_SET(flags, BTRFS_SNAPSHOT_SIGTERM) ? COPY_SIGTERM : 0),
                                 progress_path,

src/shared/copy.c

@@ -652,7 +652,7 @@ static int fd_copy_regular(
                 r = -errno;
 
         (void) futimens(fdt, (struct timespec[]) { st->st_atim, st->st_mtim });
-        (void) copy_xattr(fdf, fdt);
+        (void) copy_xattr(fdf, fdt, copy_flags);
 
         if (copy_flags & COPY_FSYNC) {
                 if (fsync(fdt) < 0) {
@@ -945,7 +945,7 @@ static int fd_copy_directory(
                 if (fchmod(fdt, st->st_mode & 07777) < 0)
                         r = -errno;
 
-                (void) copy_xattr(dirfd(d), fdt);
+                (void) copy_xattr(dirfd(d), fdt, copy_flags);
                 (void) futimens(fdt, (struct timespec[]) { st->st_atim, st->st_mtim });
         }
 
@@ -1139,7 +1139,7 @@ int copy_file_fd_full(
 
         if (S_ISREG(fdt)) {
                 (void) copy_times(fdf, fdt, copy_flags);
-                (void) copy_xattr(fdf, fdt);
+                (void) copy_xattr(fdf, fdt, copy_flags);
         }
 
         if (copy_flags & COPY_FSYNC_FULL) {
@@ -1211,7 +1211,7 @@ int copy_file_full(
                 goto fail;
 
         (void) copy_times(fdf, fdt, copy_flags);
-        (void) copy_xattr(fdf, fdt);
+        (void) copy_xattr(fdf, fdt, copy_flags);
 
         if (chattr_mask != 0)
                 (void) chattr_fd(fdt, chattr_flags, chattr_mask & ~CHATTR_EARLY_FL, NULL);
@@ -1399,7 +1399,7 @@ int copy_rights_with_fallback(int fdf, int fdt, const char *patht) {
         return fchmod_and_chown_with_fallback(fdt, patht, st.st_mode & 07777, st.st_uid, st.st_gid);
 }
 
-int copy_xattr(int fdf, int fdt) {
+int copy_xattr(int fdf, int fdt, CopyFlags copy_flags) {
         _cleanup_free_ char *names = NULL;
         int ret = 0, r;
         const char *p;
@@ -1411,7 +1411,7 @@ int copy_xattr(int fdf, int fdt) {
         NULSTR_FOREACH(p, names) {
                 _cleanup_free_ char *value = NULL;
 
-                if (!startswith(p, "user."))
+                if (!(copy_flags & COPY_ALL_XATTRS) && !startswith(p, "user."))
                         continue;
 
                 r = fgetxattr_malloc(fdf, p, &value);

src/shared/copy.h

@@ -23,6 +23,7 @@ typedef enum CopyFlags {
         COPY_FSYNC       = 1 << 10, /* fsync() after we are done */
         COPY_FSYNC_FULL  = 1 << 11, /* fsync_full() after we are done */
         COPY_SYNCFS      = 1 << 12, /* syncfs() the *top-level* dir after we are done */
+        COPY_ALL_XATTRS  = 1 << 13, /* Preserve all xattrs when copying, not just those in the user namespace */
 } CopyFlags;
 
 typedef int (*copy_progress_bytes_t)(uint64_t n_bytes, void *userdata);
@@ -72,4 +73,4 @@ int copy_rights_with_fallback(int fdf, int fdt, const char *patht);
 static inline int copy_rights(int fdf, int fdt) {
         return copy_rights_with_fallback(fdf, fdt, NULL); /* no fallback */
 }
-int copy_xattr(int fdf, int fdt);
+int copy_xattr(int fdf, int fdt, CopyFlags copy_flags);