On Wed, 7 Aug 2013 17:11:49 -0400, Josef Bacik wrote:
> There is no reason we can't just set the path to blocking and then do normal
> GFP_NOFS allocations for these extent buffers. Thanks,
>
> Signed-off-by: Josef Bacik <jba...@fusionio.com>
You've forgotten at least one place.
static inline struct extent_buffer *
get_old_root(struct btrfs_root *root, u64 time_seq)
{
...
eb_root = btrfs_read_lock_root_node(root);
...
} else {
eb = btrfs_clone_extent_buffer(eb_root);
btrfs_tree_read_unlock(eb_root);
The xfstest btrfs/004 (backref testing) discovered this issue in the
context of ioctl(BTRFS_IOC_LOGICAL_INO).
> ---
> fs/btrfs/ctree.c | 16 ++++++++++------
> fs/btrfs/extent_io.c | 8 ++++----
> 2 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index 1dd8a71..414a2d7 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -1191,8 +1191,8 @@ __tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
> struct extent_buffer *eb,
> * is freed (its refcount is decremented).
> */
> static struct extent_buffer *
> -tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
> - u64 time_seq)
> +tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
> + struct extent_buffer *eb, u64 time_seq)
> {
> struct extent_buffer *eb_rewin;
> struct tree_mod_elem *tm;
> @@ -1207,12 +1207,15 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
> struct extent_buffer *eb,
> if (!tm)
> return eb;
>
> + btrfs_set_path_blocking(path);
> + btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
> +
> if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
> BUG_ON(tm->slot != 0);
> eb_rewin = alloc_dummy_extent_buffer(eb->start,
> fs_info->tree_root->nodesize);
> if (!eb_rewin) {
> - btrfs_tree_read_unlock(eb);
> + btrfs_tree_read_unlock_blocking(eb);
> free_extent_buffer(eb);
> return NULL;
> }
> @@ -1224,13 +1227,14 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
> struct extent_buffer *eb,
> } else {
> eb_rewin = btrfs_clone_extent_buffer(eb);
> if (!eb_rewin) {
> - btrfs_tree_read_unlock(eb);
> + btrfs_tree_read_unlock_blocking(eb);
> free_extent_buffer(eb);
> return NULL;
> }
> }
>
> - btrfs_tree_read_unlock(eb);
> + btrfs_clear_path_blocking(path, NULL, BTRFS_READ_LOCK);
> + btrfs_tree_read_unlock_blocking(eb);
> free_extent_buffer(eb);
>
> extent_buffer_get(eb_rewin);
> @@ -2779,7 +2783,7 @@ again:
> btrfs_clear_path_blocking(p, b,
> BTRFS_READ_LOCK);
> }
> - b = tree_mod_log_rewind(root->fs_info, b, time_seq);
> + b = tree_mod_log_rewind(root->fs_info, p, b, time_seq);
> if (!b) {
> ret = -ENOMEM;
> goto done;
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index b422cba..beda5a8 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -4340,12 +4340,12 @@ struct extent_buffer
> *btrfs_clone_extent_buffer(struct extent_buffer *src)
> struct extent_buffer *new;
> unsigned long num_pages = num_extent_pages(src->start, src->len);
>
> - new = __alloc_extent_buffer(NULL, src->start, src->len, GFP_ATOMIC);
> + new = __alloc_extent_buffer(NULL, src->start, src->len, GFP_NOFS);
Here.
> if (new == NULL)
> return NULL;
>
> for (i = 0; i < num_pages; i++) {
> - p = alloc_page(GFP_ATOMIC);
> + p = alloc_page(GFP_NOFS);
> if (!p) {
> btrfs_release_extent_buffer(new);
> return NULL;
> @@ -4369,12 +4369,12 @@ struct extent_buffer *alloc_dummy_extent_buffer(u64
> start, unsigned long len)
> unsigned long num_pages = num_extent_pages(0, len);
> unsigned long i;
>
> - eb = __alloc_extent_buffer(NULL, start, len, GFP_ATOMIC);
> + eb = __alloc_extent_buffer(NULL, start, len, GFP_NOFS);
> if (!eb)
> return NULL;
>
> for (i = 0; i < num_pages; i++) {
> - eb->pages[i] = alloc_page(GFP_ATOMIC);
> + eb->pages[i] = alloc_page(GFP_NOFS);
> if (!eb->pages[i])
> goto err;
> }
>
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