Since a zero-length dedupe operation is guaranteed to succeed, use that
to test whether or not this filesystem supports dedupe.
Signed-off-by: Darrick J. Wong <darrick.w...@oracle.com>
---
v2: declare variables on the stack instead of introducing fake types
---
file_scan.c | 45 +++++++++++++++++++++++++++++++++++----------
1 file changed, 35 insertions(+), 10 deletions(-)
diff --git a/file_scan.c b/file_scan.c
index 617f166..2708bfe 100644
--- a/file_scan.c
+++ b/file_scan.c
@@ -45,11 +45,7 @@
#include "file_scan.h"
#include "dbfile.h"
#include "util.h"
-
-/* This is not in linux/magic.h */
-#ifndef XFS_SB_MAGIC
-#define XFS_SB_MAGIC 0x58465342 /* 'XFSB' */
-#endif
+#include "btrfs-ioctl.h"
static char path[PATH_MAX] = { 0, };
static char *pathp = path;
@@ -189,6 +185,37 @@ static int walk_dir(const char *name)
return ret;
}
+/*
+ * A zero-length dedupe between two files should always succeed,
+ * so we can use this to test the presence of dedupe functionality.
+ */
+static bool check_ioctl_works(int fd)
+{
+ struct {
+ struct btrfs_ioctl_same_args args;
+ struct btrfs_ioctl_same_extent_info info;
+ } sa = {0};
+ struct stat sb;
+ static int cached = -1;
+ int ret;
+
+ if (cached >= 0)
+ return cached != 0;
+
+ ret = fstat(fd, &sb);
+ if (ret)
+ return false;
+
+ sa.args.dest_count = 1;
+ sa.args.length = 0;
+ sa.info.fd = fd;
+ sa.info.logical_offset = 0;
+ errno = 0;
+ ret = btrfs_extent_same(fd, &sa.args);
+ cached = !ret && !errno && !sa.info.status;
+ return cached;
+}
+
static int __add_file(const char *name, struct stat *st,
struct filerec **ret_file)
{
@@ -235,12 +262,10 @@ static int __add_file(const char *name, struct stat *st,
goto out;
}
- if (run_dedupe &&
- ((fs.f_type != BTRFS_SUPER_MAGIC &&
- fs.f_type != XFS_SB_MAGIC))) {
+ if (run_dedupe && !check_ioctl_works(fd)) {
close(fd);
- fprintf(stderr, "\"%s\": Can only dedupe files on btrfs or xfs "
- "(experimental)\n", name);
+ fprintf(stderr, "\"%s\": dedupe ioctl not supported on this "
+ "filesystem.\n", name);
return ENOSYS;
}
--
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