[Btrfs-devel] In correct usage of IS_ERR() in extent_io.c

[Peter Teoh]

Please correct me if wrong.   kmem_cache_alloc() based API should not
call IS_ERR() to check on error.   Similarly, many usage of IS_ERR()
is not correct, as it will lead to returning an error condition when
there is no error.   Self-explanatory as in the following err.h header
declaration:

#define MAX_ERRNO       4095

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

static inline long IS_ERR(const void *ptr)
{
        return IS_ERR_VALUE((unsigned long)ptr);
}

Signed-off-by: Peter Teoh <htmldeveloper at gmail.com>

--- extent_io.c.orig    2008-03-15 12:33:37.000000000 +0800
+++ extent_io.c 2008-03-16 10:32:23.000000000 +0800
@@ -111,7 +111,7 @@ struct extent_state *alloc_extent_state(
        struct extent_state *state;

        state = kmem_cache_alloc(extent_state_cache, mask);
-       if (!state || IS_ERR(state))
+       if (!state)
                return state;
        state->state = 0;
        state->private = 0;
@@ -941,7 +941,7 @@ int find_first_extent_bit(struct extent_
         * our range starts.
         */
        node = tree_search(tree, start);
-       if (!node || IS_ERR(node)) {
+       if (!node) {
                goto out;
        }

@@ -974,7 +974,7 @@ struct extent_state *find_first_extent_b
         * our range starts.
         */
        node = tree_search(tree, start);
-       if (!node || IS_ERR(node)) {
+       if (!node) {
                goto out;
        }

@@ -1008,7 +1008,7 @@ u64 find_lock_delalloc_range(struct exte
         */
 search_again:
        node = tree_search(tree, cur_start);
-       if (!node || IS_ERR(node)) {
+       if (!node) {
                *end = (u64)-1;
                goto out;
        }
@@ -1096,7 +1096,7 @@ u64 count_range_bits(struct extent_io_tr
         * our range starts.
         */
        node = tree_search(tree, cur_start);
-       if (!node || IS_ERR(node)) {
+       if (!node) {
                goto out;
        }

@@ -1197,7 +1197,7 @@ int set_state_private(struct extent_io_t
         * our range starts.
         */
        node = tree_search(tree, start);
-       if (!node || IS_ERR(node)) {
+       if (!node) {
                ret = -ENOENT;
                goto out;
        }
@@ -1224,7 +1224,7 @@ int get_state_private(struct extent_io_t
         * our range starts.
         */
        node = tree_search(tree, start);
-       if (!node || IS_ERR(node)) {
+       if (!node) {
                ret = -ENOENT;
                goto out;
        }
@@ -2616,7 +2616,7 @@ struct extent_buffer *alloc_extent_buffe
        int uptodate = 1;

        eb = __alloc_extent_buffer(tree, start, len, mask);
-       if (!eb || IS_ERR(eb))
+       if (!eb)
                return NULL;

        if (eb->flags & EXTENT_BUFFER_FILLED)
@@ -2691,7 +2691,7 @@ struct extent_buffer *find_extent_buffer
        int uptodate = 1;

        eb = __alloc_extent_buffer(tree, start, len, mask);
-       if (!eb || IS_ERR(eb))
+       if (!eb)
                return NULL;

        if (eb->flags & EXTENT_BUFFER_FILLED)


-- 
Regards,
Peter Teoh