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authornpiggin@suse.de <npiggin@suse.de>2009-04-26 20:25:55 +1000
committerAl Viro <viro@zeniv.linux.org.uk>2009-06-11 21:36:02 -0400
commit96029c4e09ccbd73a6d0ed2b29e80bf2586ad7ef (patch)
tree032d2ac7024250c18487a2c7122af68fe56567ff /include
parentd3ef3d7351ccfbef3e5d926efc5ee332136f40d4 (diff)
downloadlinux-96029c4e09ccbd73a6d0ed2b29e80bf2586ad7ef.tar.bz2
fs: introduce mnt_clone_write
This patch speeds up lmbench lat_mmap test by about another 2% after the first patch. Before: avg = 462.286 std = 5.46106 After: avg = 453.12 std = 9.58257 (50 runs of each, stddev gives a reasonable confidence) It does this by introducing mnt_clone_write, which avoids some heavyweight operations of mnt_want_write if called on a vfsmount which we know already has a write count; and mnt_want_write_file, which can call mnt_clone_write if the file is open for write. After these two patches, mnt_want_write and mnt_drop_write go from 7% on the profile down to 1.3% (including mnt_clone_write). [AV: mnt_want_write_file() should take file alone and derive mnt from it; not only all callers have that form, but that's the only mnt about which we know that it's already held for write if file is opened for write] Cc: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mount.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/mount.h b/include/linux/mount.h
index ac49c1f8e5c0..5d5275364867 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -88,7 +88,11 @@ static inline struct vfsmount *mntget(struct vfsmount *mnt)
return mnt;
}
+struct file; /* forward dec */
+
extern int mnt_want_write(struct vfsmount *mnt);
+extern int mnt_want_write_file(struct file *file);
+extern int mnt_clone_write(struct vfsmount *mnt);
extern void mnt_drop_write(struct vfsmount *mnt);
extern void mntput_no_expire(struct vfsmount *mnt);
extern void mnt_pin(struct vfsmount *mnt);