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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 /fs/open.c
parentd3ef3d7351ccfbef3e5d926efc5ee332136f40d4 (diff)
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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 'fs/open.c')
-rw-r--r--fs/open.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/open.c b/fs/open.c
index bdfbf03615a..7200e23d925 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -612,7 +612,7 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
audit_inode(NULL, dentry);
- err = mnt_want_write(file->f_path.mnt);
+ err = mnt_want_write_file(file);
if (err)
goto out_putf;
mutex_lock(&inode->i_mutex);
@@ -761,7 +761,7 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
if (!file)
goto out;
- error = mnt_want_write(file->f_path.mnt);
+ error = mnt_want_write_file(file);
if (error)
goto out_fput;
dentry = file->f_path.dentry;