btrfs: fix race between quota disable and quota assign ioctls

[platform/kernel/linux-rpi.git] / lib / iov_iter.c

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index b137da9..d0c3e93 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -514,6 +514,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
        WARN_ON(direction & ~(READ | WRITE));
        *i = (struct iov_iter) {
                .iter_type = ITER_IOVEC,
+               .nofault = false,
                .data_source = direction,
                .iov = iov,
                .nr_segs = nr_segs,
@@ -690,6 +691,7 @@ static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
        struct pipe_inode_info *pipe = i->pipe;
        unsigned int p_mask = pipe->ring_size - 1;
        unsigned int i_head;
+       unsigned int valid = pipe->head;
        size_t n, off, xfer = 0;
 
        if (!sanity(i))
@@ -703,11 +705,17 @@ static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
                rem = copy_mc_to_kernel(p + off, addr + xfer, chunk);
                chunk -= rem;
                kunmap_local(p);
-               i->head = i_head;
-               i->iov_offset = off + chunk;
-               xfer += chunk;
-               if (rem)
+               if (chunk) {
+                       i->head = i_head;
+                       i->iov_offset = off + chunk;
+                       xfer += chunk;
+                       valid = i_head + 1;
+               }
+               if (rem) {
+                       pipe->bufs[i_head & p_mask].len -= rem;
+                       pipe_discard_from(pipe, valid);
                        break;
+               }
                n -= chunk;
                off = 0;
                i_head++;
@@ -1435,7 +1443,7 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
 {
        unsigned nr, offset;
        pgoff_t index, count;
-       size_t size = maxsize, actual;
+       size_t size = maxsize;
        loff_t pos;
 
        if (!size || !maxpages)
@@ -1462,13 +1470,7 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
        if (nr == 0)
                return 0;
 
-       actual = PAGE_SIZE * nr;
-       actual -= offset;
-       if (nr == count && size > 0) {
-               unsigned last_offset = (nr > 1) ? 0 : offset;
-               actual -= PAGE_SIZE - (last_offset + size);
-       }
-       return actual;
+       return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
 }
 
 /* must be done on non-empty ITER_IOVEC one */
@@ -1529,13 +1531,17 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
                return 0;
 
        if (likely(iter_is_iovec(i))) {
+               unsigned int gup_flags = 0;
                unsigned long addr;
 
+               if (iov_iter_rw(i) != WRITE)
+                       gup_flags |= FOLL_WRITE;
+               if (i->nofault)
+                       gup_flags |= FOLL_NOFAULT;
+
                addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
                n = DIV_ROUND_UP(len, PAGE_SIZE);
-               res = get_user_pages_fast(addr, n,
-                               iov_iter_rw(i) != WRITE ?  FOLL_WRITE : 0,
-                               pages);
+               res = get_user_pages_fast(addr, n, gup_flags, pages);
                if (unlikely(res <= 0))
                        return res;
                return (res == n ? len : res * PAGE_SIZE) - *start;
@@ -1599,7 +1605,7 @@ static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
        struct page **p;
        unsigned nr, offset;
        pgoff_t index, count;
-       size_t size = maxsize, actual;
+       size_t size = maxsize;
        loff_t pos;
 
        if (!size)
@@ -1628,13 +1634,7 @@ static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
        if (nr == 0)
                return 0;
 
-       actual = PAGE_SIZE * nr;
-       actual -= offset;
-       if (nr == count && size > 0) {
-               unsigned last_offset = (nr > 1) ? 0 : offset;
-               actual -= PAGE_SIZE - (last_offset + size);
-       }
-       return actual;
+       return min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
 }
 
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
@@ -1651,15 +1651,20 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
                return 0;
 
        if (likely(iter_is_iovec(i))) {
+               unsigned int gup_flags = 0;
                unsigned long addr;
 
+               if (iov_iter_rw(i) != WRITE)
+                       gup_flags |= FOLL_WRITE;
+               if (i->nofault)
+                       gup_flags |= FOLL_NOFAULT;
+
                addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
                n = DIV_ROUND_UP(len, PAGE_SIZE);
                p = get_pages_array(n);
                if (!p)
                        return -ENOMEM;
-               res = get_user_pages_fast(addr, n,
-                               iov_iter_rw(i) != WRITE ?  FOLL_WRITE : 0, p);
+               res = get_user_pages_fast(addr, n, gup_flags, p);
                if (unlikely(res <= 0)) {
                        kvfree(p);
                        *pages = NULL;