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author | Sascha Hauer <s.hauer@pengutronix.de> | 2018-10-17 10:33:44 +0200 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2018-10-29 12:23:34 +0100 |
commit | 4e601546388e2e2968eed3b96b1ff19c4e421c31 (patch) | |
tree | 133f70d8bbec9ab0e28e69aab970ca6e746f8f86 | |
parent | fb40e3c1cb2d5182edcd9dabfcd24e30bdf4ee25 (diff) | |
download | barebox-4e601546388e2e2968eed3b96b1ff19c4e421c31.tar.gz barebox-4e601546388e2e2968eed3b96b1ff19c4e421c31.tar.xz |
fs: implement d_revalidate
d_revalidate is useful when filesystems change under the hood of the
fs layer. This can happen with network filesystems or with devfs.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r-- | fs/fs.c | 37 | ||||
-rw-r--r-- | include/linux/dcache.h | 3 |
2 files changed, 39 insertions, 1 deletions
@@ -1141,6 +1141,12 @@ const struct qstr slash_name = QSTR_INIT("/", 1); void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) { dentry->d_op = op; + + if (!op) + return; + + if (op->d_revalidate) + dentry->d_flags |= DCACHE_OP_REVALIDATE; } /** @@ -1285,6 +1291,35 @@ void d_invalidate(struct dentry *dentry) { } +static inline int d_revalidate(struct dentry *dentry, unsigned int flags) +{ + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) + return dentry->d_op->d_revalidate(dentry, flags); + else + return 1; +} + +/* + * This looks up the name in dcache and possibly revalidates the found dentry. + * NULL is returned if the dentry does not exist in the cache. + */ +static struct dentry *lookup_dcache(const struct qstr *name, + struct dentry *dir, + unsigned int flags) +{ + struct dentry *dentry = d_lookup(dir, name); + if (dentry) { + int error = d_revalidate(dentry, flags); + if (unlikely(error <= 0)) { + if (!error) + d_invalidate(dentry); + dput(dentry); + return ERR_PTR(error); + } + } + return dentry; +} + static inline void __d_clear_type_and_inode(struct dentry *dentry) { dentry->d_flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); @@ -1496,7 +1531,7 @@ static struct dentry *__lookup_hash(const struct qstr *name, if (!base) return ERR_PTR(-ENOENT); - dentry = d_lookup(base, name); + dentry = lookup_dcache(name, base, flags); if (dentry) return dentry; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 16244129bf..1581ddc701 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -82,6 +82,7 @@ struct dentry { }; struct dentry_operations { + int (*d_revalidate)(struct dentry *, unsigned int); }; struct dentry * d_make_root(struct inode *); @@ -93,6 +94,8 @@ void d_delete(struct dentry *); struct dentry *dget(struct dentry *); void dput(struct dentry *); +#define DCACHE_OP_REVALIDATE 0x00000004 + #define DCACHE_ENTRY_TYPE 0x00700000 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */ #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */ |