2023-07-27 17:40:28

by Gabriel Krisman Bertazi

Subject: [PATCH v4 2/7] fs: Add DCACHE_CASEFOLDED_NAME flag

From: Gabriel Krisman Bertazi <[email protected]>

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 <[email protected]>
Signed-off-by: Gabriel Krisman Bertazi <[email protected]>

---
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 98521862e58a..5791489b589f 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_casefold_lookup(struct dentry *dentry)
+{
+ spin_lock(&dentry->d_lock);
+ dentry->d_flags |= DCACHE_CASEFOLDED_NAME;
+ spin_unlock(&dentry->d_lock);
+}
+EXPORT_SYMBOL(d_set_casefold_lookup);
+
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 b6188f2e8950..14aa0255bd04 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -209,6 +209,7 @@ 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
@@ -497,6 +498,13 @@ static inline bool d_is_fallthru(const struct dentry *dentry)
return dentry->d_flags & DCACHE_FALLTHRU;
}

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

extern int sysctl_vfs_cache_pressure;

--
2.41.0

2023-07-29 04:58:09

by Eric Biggers

Subject: Re: [PATCH v4 2/7] fs: Add DCACHE_CASEFOLDED_NAME flag

On Thu, Jul 27, 2023 at 01:28:38PM -0400, Gabriel Krisman Bertazi wrote:
> From: Gabriel Krisman Bertazi <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
>
> ---
> 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 98521862e58a..5791489b589f 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_casefold_lookup(struct dentry *dentry)
> +{
> + spin_lock(&dentry->d_lock);
> + dentry->d_flags |= DCACHE_CASEFOLDED_NAME;
> + spin_unlock(&dentry->d_lock);
> +}
> +EXPORT_SYMBOL(d_set_casefold_lookup);

d_set_casefolded_name()

> +static inline bool d_is_casefold_lookup(const struct dentry *dentry)
> +{
> + return dentry->d_flags & DCACHE_CASEFOLDED_NAME;
> +}

d_is_casefolded_name(). Or even better, just write 'dentry->d_flags &
DCACHE_CASEFOLDED_NAME' directly in the one place that actually needs this?

- Eric