There are 4 callers; two proceed to check if result is positive and fail with ENOENT if it isn't; one (in handle_lookup_down()) is guaranteed to yield positive and one (in lookup_fast()) is _preceded_ by positivity check. However, follow_managed() on a negative dentry is a (fairly cheap) no-op on anything other than autofs. And negative autofs dentries are never hashed, so lookup_fast() is not going to run into one of those. Moreover, successful follow_managed() on a _positive_ dentry never yields a negative one (and we significantly rely upon that in callers of lookup_fast()). In other words, we can easily transpose the positivity check and the call of follow_managed() in lookup_fast(). And that allows to fold the positivity check *into* follow_managed(), simplifying life for the code downstream of its calls.
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| @@ -440,6 +440,11 @@ static inline bool d_is_negative(const struct dentry *dentry) · 439 unmodified lines | ||
| 440 | 440 | return d_is_miss(dentry); |
| 441 | 441 | } |
| 442 | 442 | |
| 443 | +static inline bool d_flags_negative(unsigned flags) | |
| 444 | +{ | |
| 445 | + return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE; | |
| 446 | +} | |
| 447 | + | |
| 443 | 448 | static inline bool d_is_positive(const struct dentry *dentry) |
| 444 | 449 | { |
| 445 | 450 | return !d_is_negative(dentry); |