[PATCH v6 4/9] fs: Add DCACHE_CASEFOLDED_NAME flag

Gabriel Krisman Bertazi
2023-08-16T05:09:17Z

From: Gabriel Krisman Bertazi <krisman@collabora.com>

This flag marks a negative or positive dentry as being created after a
case-insensitive lookup operation. It is useful to differentiate
dentries this way to detect whether the negative dentry can be trusted
during a case-insensitive lookup.

Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v5:
- Fix EXPORT_SYMBOL (Eric, kernel test bot)
Changes since v4:
- Fixup names of functions to reflect flag name change (Eric)

Changes since v2:
- Rename DCACHE_CASEFOLD_LOOKUP -> DCACHE_CASEFOLDED_NAME (Eric)
---
fs/dcache.c | 8 ++++++++
include/linux/dcache.h | 8 ++++++++
2 files changed, 16 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 52e6d5fdab6b..91e5cd4c4237 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1958,6 +1958,14 @@ void d_set_fallthru(struct dentry *dentry)
}
EXPORT_SYMBOL(d_set_fallthru);

+void d_set_casefolded_name(struct dentry *dentry)
+{
+ spin_lock(&dentry->d_lock);
+ dentry->d_flags |= DCACHE_CASEFOLDED_NAME;
+ spin_unlock(&dentry->d_lock);
+}
+EXPORT_SYMBOL(d_set_casefolded_name);
+
static unsigned d_flags_for_inode(struct inode *inode)
{
unsigned add_flags = DCACHE_REGULAR_TYPE;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 9362e4ef0bad..ccbb5c4db7ce 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -208,6 +208,7 @@ struct dentry_operations {
#define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
#define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */
#define DCACHE_OP_REAL 0x04000000
+#define DCACHE_CASEFOLDED_NAME 0x08000000 /* Dentry comes from a casefold directory */

#define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
#define DCACHE_DENTRY_CURSOR 0x20000000
@@ -496,6 +497,13 @@ static inline bool d_is_fallthru(const struct dentry *dentry)
return dentry->d_flags & DCACHE_FALLTHRU;
}

+extern void d_set_casefolded_name(struct dentry *dentry);
+
+static inline bool d_is_casefolded_name(const struct dentry *dentry)
+{
+ return dentry->d_flags & DCACHE_CASEFOLDED_NAME;
+}
+

extern int sysctl_vfs_cache_pressure;

--
2.41.0