fs: Verify write lifetime constants at compile time

The code in fs/fcntl.c converts RWH_* constants to and from WRITE_LIFE_*
constants using casts. Verify at compile time that these casts will yield
the intended effect.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240202203926.2478590-3-bvanassche@acm.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 3ff707bf2743a6fb5b0c2064cc510ab984230641..f3bc4662455fe3306e9a60058e20498ebffd34d1 100644 (file)
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -270,6 +270,13 @@ static int f_getowner_uids(struct file *filp, unsigned long arg)
 
 static bool rw_hint_valid(u64 hint)
 {
+       BUILD_BUG_ON(WRITE_LIFE_NOT_SET != RWH_WRITE_LIFE_NOT_SET);
+       BUILD_BUG_ON(WRITE_LIFE_NONE != RWH_WRITE_LIFE_NONE);
+       BUILD_BUG_ON(WRITE_LIFE_SHORT != RWH_WRITE_LIFE_SHORT);
+       BUILD_BUG_ON(WRITE_LIFE_MEDIUM != RWH_WRITE_LIFE_MEDIUM);
+       BUILD_BUG_ON(WRITE_LIFE_LONG != RWH_WRITE_LIFE_LONG);
+       BUILD_BUG_ON(WRITE_LIFE_EXTREME != RWH_WRITE_LIFE_EXTREME);
+
        switch (hint) {
        case RWH_WRITE_LIFE_NOT_SET:
        case RWH_WRITE_LIFE_NONE: