From 7129ed0ff069fde418773be313442beb0dacfaaf Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Tue, 7 May 2024 12:48:30 -0400 Subject: stat: Prefer fstat(fd) to fstatat(fd, "", AT_EMPTY_PATH) This lets us get rid of the runtime probe for AT_EMPTY_PATH support, and should be more efficient anyway. We still use statx(fd, "", AT_EMPTY_PATH) if available. Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wiYnnv7Kw7v+Cp2xU6_Fd-qxQMZuuxZ61LgA2=Gtftw-A@mail.gmail.com/ --- src/stat.c | 32 +++++++++++++------------------- 1 file changed, 13 insertions(+), 19 deletions(-) diff --git a/src/stat.c b/src/stat.c index f5cf3fe..db1f99a 100644 --- a/src/stat.c +++ b/src/stat.c @@ -297,27 +297,21 @@ int bfs_stat(int at_fd, const char *at_path, enum bfs_stat_flags flags, struct b return bfs_stat_tryfollow(at_fd, at_path, at_flags, flags, buf); } - // Check __GNU__ to work around https://lists.gnu.org/archive/html/bug-hurd/2021-12/msg00001.html -#if defined(AT_EMPTY_PATH) && !__GNU__ - static atomic bool has_at_ep = true; - if (load(&has_at_ep, relaxed)) { - at_flags |= AT_EMPTY_PATH; - int ret = bfs_stat_explicit(at_fd, "", at_flags, buf); - if (ret != 0 && errno == EINVAL) { - store(&has_at_ep, false, relaxed); - } else { - return ret; - } - } -#endif - - struct stat statbuf; - if (fstat(at_fd, &statbuf) == 0) { - bfs_stat_convert(buf, &statbuf); - return 0; - } else { +#if BFS_USE_STATX + // If we have statx(), use it with AT_EMPTY_PATH for its extra features + at_flags |= AT_EMPTY_PATH; + return bfs_stat_explicit(at_fd, "", at_flags, buf); +#else + // Otherwise, just use fstat() rather than fstatat(at_fd, ""), to save + // the kernel the trouble of copying in the empty string + struct stat sb; + if (fstat(at_fd, &sb) != 0) { return -1; } + + bfs_stat_convert(buf, &sb); + return 0; +#endif } const struct timespec *bfs_stat_time(const struct bfs_stat *buf, enum bfs_stat_field field) { -- cgit v1.2.3