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From: Mateusz Guzik <mjguzik@gmail.com>
To: brauner@kernel.org
Cc: viro@zeniv.linux.org.uk,
jack@suse.cz,
linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
Mateusz Guzik <mjguzik@gmail.com>
Subject: [MEH PATCH] fs: make generic_fillattr() tail-callable and utilize it
in ext2/ext4
Date: Tue, 1 Apr 2025 18:18:13 +0200
Message-ID: <20250401161813.1121828-1-mjguzik@gmail.com>
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Unfortunately the other filesystems I checked make adjustments after
their own call to generic_fillattr() and consequently can't benefit.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
---
There are weird slowdowns on fstat, this is a byproduct of trying to
straighten out the fast path.
Not benchmarked, but I did confirm the compiler jmps out to the routine
instead of emitting a call which is the right thing to do here.
that said I'm not going to argue, but I like to see this out of the way.
there are nasty things which need to be addressed separately
fs/ext2/inode.c | 3 +--
fs/ext4/inode.c | 3 +--
fs/stat.c | 6 +++++-
include/linux/fs.h | 2 +-
4 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 30f8201c155f..cf1f89922207 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1629,8 +1629,7 @@ int ext2_getattr(struct mnt_idmap *idmap, const struc=
t path *path,
STATX_ATTR_IMMUTABLE |
STATX_ATTR_NODUMP);
=20
- generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
- return 0;
+ return generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
}
=20
int ext2_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1dc09ed5d403..3edd6e60dd9b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5687,8 +5687,7 @@ int ext4_getattr(struct mnt_idmap *idmap, const struc=
t path *path,
STATX_ATTR_NODUMP |
STATX_ATTR_VERITY);
=20
- generic_fillattr(idmap, request_mask, inode, stat);
- return 0;
+ return generic_fillattr(idmap, request_mask, inode, stat);
}
=20
int ext4_file_getattr(struct mnt_idmap *idmap,
diff --git a/fs/stat.c b/fs/stat.c
index f13308bfdc98..581a95376e70 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -78,8 +78,11 @@ EXPORT_SYMBOL(fill_mg_cmtime);
* take care to map the inode according to @idmap before filling in the
* uid and gid filds. On non-idmapped mounts or if permission checking is =
to be
* performed on the raw inode simply pass @nop_mnt_idmap.
+ *
+ * The routine always succeeds. We make it return a value so that consumer=
s can
+ * tail-call it.
*/
-void generic_fillattr(struct mnt_idmap *idmap, u32 request_mask,
+int generic_fillattr(struct mnt_idmap *idmap, u32 request_mask,
struct inode *inode, struct kstat *stat)
{
vfsuid_t vfsuid =3D i_uid_into_vfsuid(idmap, inode);
@@ -110,6 +113,7 @@ void generic_fillattr(struct mnt_idmap *idmap, u32 requ=
est_mask,
stat->change_cookie =3D inode_query_iversion(inode);
}
=20
+ return 0;
}
EXPORT_SYMBOL(generic_fillattr);
=20
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 016b0fe1536e..754893d8d2a8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3471,7 +3471,7 @@ extern int page_symlink(struct inode *inode, const ch=
ar *symname, int len);
extern const struct inode_operations page_symlink_inode_operations;
extern void kfree_link(void *);
void fill_mg_cmtime(struct kstat *stat, u32 request_mask, struct inode *in=
ode);
-void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct ksta=
t *);
+int generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat=
*);
void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
void generic_fill_statx_atomic_writes(struct kstat *stat,
unsigned int unit_min,
--=20
2.43.0