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fuse: optimize __fuse_direct_io()

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__fuse_direct_io() allocates fuse-requests by calling fuse_get_req(fc, n). The
patch calculates 'n' based on iov[] array. This is useful because allocating
FUSE_MAX_PAGES_PER_REQ page pointers and descriptors for each fuse request
would be waste of memory in case of iov-s of smaller size.

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Maxim Patlasov 2012-10-26 19:50:36 +04:00 committed by Miklos Szeredi
parent 7c190c8b9c
commit 5565a9d884
1 changed files with 21 additions and 4 deletions
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25
fs/fuse/file.c
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@ -1088,14 +1088,14 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
return 0;
}
while (nbytes < *nbytesp && req->num_pages < FUSE_MAX_PAGES_PER_REQ) {
while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
unsigned npages;
unsigned long user_addr = fuse_get_user_addr(ii);
unsigned offset = user_addr & ~PAGE_MASK;
size_t frag_size = fuse_get_frag_size(ii, *nbytesp - nbytes);
int ret;
unsigned n = FUSE_MAX_PAGES_PER_REQ - req->num_pages;
unsigned n = req->max_pages - req->num_pages;
frag_size = min_t(size_t, frag_size, n << PAGE_SHIFT);
npages = (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
@ -1131,6 +1131,23 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
return 0;
}
static inline int fuse_iter_npages(const struct iov_iter *ii_p)
{
struct iov_iter ii = *ii_p;
int npages = 0;
while (iov_iter_count(&ii) && npages < FUSE_MAX_PAGES_PER_REQ) {
unsigned long user_addr = fuse_get_user_addr(&ii);
unsigned offset = user_addr & ~PAGE_MASK;
size_t frag_size = iov_iter_single_seg_count(&ii);
npages += (frag_size + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
iov_iter_advance(&ii, frag_size);
}
return min(npages, FUSE_MAX_PAGES_PER_REQ);
}
static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
unsigned long nr_segs, size_t count,
loff_t *ppos, int write)
@ -1145,7 +1162,7 @@ static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
iov_iter_init(&ii, iov, nr_segs, count, 0);
req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
req = fuse_get_req(fc, fuse_iter_npages(&ii));
if (IS_ERR(req))
return PTR_ERR(req);
@ -1180,7 +1197,7 @@ static ssize_t __fuse_direct_io(struct file *file, const struct iovec *iov,
break;
if (count) {
fuse_put_request(fc, req);
req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
req = fuse_get_req(fc, fuse_iter_npages(&ii));
if (IS_ERR(req))
break;
}