btrfs: avoid link error with CONFIG_NO_AUTO_INLINE

arndb · kdave · commit 7e17916b3579 · 2018-11-06T16:42:08.000+01:00
Note: this patch fixes a problem in a feature outside of btrfs ("kernel hacking: add a config option to disable compiler auto-inlining") and is applied ahead of time due to cross-subsystem dependencies. On 32-bit ARM with gcc-8, I see a link error with the addition of the CONFIG_NO_AUTO_INLINE option: fs/btrfs/super.o: In function `btrfs_statfs': super.c:(.text+0x67b8): undefined reference to `__aeabi_uldivmod' super.c:(.text+0x67fc): undefined reference to `__aeabi_uldivmod' super.c:(.text+0x6858): undefined reference to `__aeabi_uldivmod' super.c:(.text+0x6920): undefined reference to `__aeabi_uldivmod' super.c:(.text+0x693c): undefined reference to `__aeabi_uldivmod' fs/btrfs/super.o:super.c:(.text+0x6958): more undefined references to `__aeabi_uldivmod' follow So far this is the only file that shows the behavior, so I'd propose to just work around it by marking the functions as 'static inline' that normally get inlined here. The reference to __aeabi_uldivmod comes from a div_u64() which has an optimization for a constant division that uses a straight '/' operator when the result should be known to the compiler. My interpretation is that as we turn off inlining, gcc still expects the result to be constant but fails to use that constant value. Link: https://lkml.kernel.org/r/20181103153941.1881966-1-arnd@arndb.de Reviewed-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> [ add the note ] Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
@@ -1916,7 +1916,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 }
 
 /* Used to sort the devices by max_avail(descending sort) */
-static int btrfs_cmp_device_free_bytes(const void *dev_info1,
+static inline int btrfs_cmp_device_free_bytes(const void *dev_info1,
 				       const void *dev_info2)
 {
 	if (((struct btrfs_device_info *)dev_info1)->max_avail >
@@ -1945,8 +1945,8 @@ static inline void btrfs_descending_sort_devices(
  * The helper to calc the free space on the devices that can be used to store
  * file data.
  */
-static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
-				       u64 *free_bytes)
+static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
+					      u64 *free_bytes)
 {
 	struct btrfs_device_info *devices_info;
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;

Original file line number	Diff line number	Diff line change
`@@ -1916,7 +1916,7 @@ static int btrfs_remount(struct super_block sb, int flags, char *data)`
`1916`	`1916`	`}`
`1917`	`1917`
`1918`	`1918`	`/* Used to sort the devices by max_avail(descending sort) */`
`1919`		`-static int btrfs_cmp_device_free_bytes(const void *dev_info1,`
	`1919`	`+static inline int btrfs_cmp_device_free_bytes(const void *dev_info1,`
`1920`	`1920`	`const void *dev_info2)`
`1921`	`1921`	`{`
`1922`	`1922`	`if (((struct btrfs_device_info *)dev_info1)->max_avail >`
`@@ -1945,8 +1945,8 @@ static inline void btrfs_descending_sort_devices(`
`1945`	`1945`	`* The helper to calc the free space on the devices that can be used to store`
`1946`	`1946`	`* file data.`
`1947`	`1947`	`*/`
`1948`		`-static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,`
`1949`		`- u64 *free_bytes)`
	`1948`	`+static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,`
	`1949`	`+ u64 *free_bytes)`
`1950`	`1950`	`{`
`1951`	`1951`	`struct btrfs_device_info *devices_info;`
`1952`	`1952`	`struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;`