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authorLinus Torvalds <torvalds@linux-foundation.org>2013-09-12 12:40:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-12 12:40:15 -0700
commit3272c544da48f8915a0e34189182aed029bd0f2b (patch)
treee2d6aacc2de8f26c14e844af6ed245b8a43d7978 /fs/dcache.c
parentff812d724254b95df76b7775d1359d856927a840 (diff)
downloadop-kernel-dev-3272c544da48f8915a0e34189182aed029bd0f2b.zip
op-kernel-dev-3272c544da48f8915a0e34189182aed029bd0f2b.tar.gz
vfs: use __getname/__putname for getcwd() system call
It's a pathname. It should use the pathname allocators and deallocators, and PATH_MAX instead of PAGE_SIZE. Never mind that the two are commonly the same. With this, the allocations scale up nicely too, and I can do getcwd() system calls at a rate of about 300M/s, with no lock contention anywhere. Of course, nobody sane does that, especially since getcwd() is traditionally a very slow operation in Unix. But this was also the simplest way to benchmark the prepend_path() improvements by Waiman, and once I saw the profiles I couldn't leave it well enough alone. But apart from being an performance improvement (from using per-cpu slab allocators instead of the raw page allocator), it's actually a valid and real cleanup. Signed-off-by: Linus "OCD" Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/dcache.c')
-rw-r--r--fs/dcache.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 29d5821..91e551b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3049,7 +3049,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
{
int error;
struct path pwd, root;
- char *page = (char *) __get_free_page(GFP_USER);
+ char *page = __getname();
if (!page)
return -ENOMEM;
@@ -3061,8 +3061,8 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
br_read_lock(&vfsmount_lock);
if (!d_unlinked(pwd.dentry)) {
unsigned long len;
- char *cwd = page + PAGE_SIZE;
- int buflen = PAGE_SIZE;
+ char *cwd = page + PATH_MAX;
+ int buflen = PATH_MAX;
prepend(&cwd, &buflen, "\0", 1);
error = prepend_path(&pwd, &root, &cwd, &buflen);
@@ -3080,7 +3080,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
}
error = -ERANGE;
- len = PAGE_SIZE + page - cwd;
+ len = PATH_MAX + page - cwd;
if (len <= size) {
error = len;
if (copy_to_user(buf, cwd, len))
@@ -3092,7 +3092,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
}
out:
- free_page((unsigned long) page);
+ __putname(page);
return error;
}
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