Re: [PATCH v4 2/5] dax: relocate some dax functions

Jan Kara
2017-07-24T11:35:49Z

On Fri 21-07-17 16:39:52, Ross Zwisler wrote:
> dax_load_hole() will soon need to call dax_insert_mapping_entry(), so it
> needs to be moved lower in dax.c so the definition exists.
>
> dax_wake_mapping_entry_waiter() will soon be removed from dax.h and be made
> static to dax.c, so we need to move its definition above all its callers.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/dax.c | 138 +++++++++++++++++++++++++++++++--------------------------------
> 1 file changed, 69 insertions(+), 69 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index c844a51..779dc5e 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -121,6 +121,31 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mo
> }
>
> /*
> + * We do not necessarily hold the mapping->tree_lock when we call this
> + * function so it is possible that 'entry' is no longer a valid item in the
> + * radix tree. This is okay because all we really need to do is to find the
> + * correct waitqueue where tasks might be waiting for that old 'entry' and
> + * wake them.
> + */
> +void dax_wake_mapping_entry_waiter(struct address_space *mapping,
> + pgoff_t index, void *entry, bool wake_all)
> +{
> + struct exceptional_entry_key key;
> + wait_queue_head_t *wq;
> +
> + wq = dax_entry_waitqueue(mapping, index, entry, &key);
> +
> + /*
> + * Checking for locked entry and prepare_to_wait_exclusive() happens
> + * under mapping->tree_lock, ditto for entry handling in our callers.
> + * So at this point all tasks that could have seen our entry locked
> + * must be in the waitqueue and the following check will see them.
> + */
> + if (waitqueue_active(wq))
> + __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
> +}
> +
> +/*
> * Check whether the given slot is locked. The function must be called with
> * mapping->tree_lock held
> */
> @@ -392,31 +417,6 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
> return entry;
> }
>
> -/*
> - * We do not necessarily hold the mapping->tree_lock when we call this
> - * function so it is possible that 'entry' is no longer a valid item in the
> - * radix tree. This is okay because all we really need to do is to find the
> - * correct waitqueue where tasks might be waiting for that old 'entry' and
> - * wake them.
> - */
> -void dax_wake_mapping_entry_waiter(struct address_space *mapping,
> - pgoff_t index, void *entry, bool wake_all)
> -{
> - struct exceptional_entry_key key;
> - wait_queue_head_t *wq;
> -
> - wq = dax_entry_waitqueue(mapping, index, entry, &key);
> -
> - /*
> - * Checking for locked entry and prepare_to_wait_exclusive() happens
> - * under mapping->tree_lock, ditto for entry handling in our callers.
> - * So at this point all tasks that could have seen our entry locked
> - * must be in the waitqueue and the following check will see them.
> - */
> - if (waitqueue_active(wq))
> - __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
> -}
> -
> static int __dax_invalidate_mapping_entry(struct address_space *mapping,
> pgoff_t index, bool trunc)
> {
> @@ -468,50 +468,6 @@ int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
> return __dax_invalidate_mapping_entry(mapping, index, false);
> }
>
> -/*
> - * The user has performed a load from a hole in the file. Allocating
> - * a new page in the file would cause excessive storage usage for
> - * workloads with sparse files. We allocate a page cache page instead.
> - * We'll kick it out of the page cache if it's ever written to,
> - * otherwise it will simply fall out of the page cache under memory
> - * pressure without ever having been dirtied.
> - */
> -static int dax_load_hole(struct address_space *mapping, void **entry,
> - struct vm_fault *vmf)
> -{
> - struct inode *inode = mapping->host;
> - struct page *page;
> - int ret;
> -
> - /* Hole page already exists? Return it... */
> - if (!radix_tree_exceptional_entry(*entry)) {
> - page = *entry;
> - goto finish_fault;
> - }
> -
> - /* This will replace locked radix tree entry with a hole page */
> - page = find_or_create_page(mapping, vmf->pgoff,
> - vmf->gfp_mask | __GFP_ZERO);
> - if (!page) {
> - ret = VM_FAULT_OOM;
> - goto out;
> - }
> -
> -finish_fault:
> - vmf->page = page;
> - ret = finish_fault(vmf);
> - vmf->page = NULL;
> - *entry = page;
> - if (!ret) {
> - /* Grab reference for PTE that is now referencing the page */
> - get_page(page);
> - ret = VM_FAULT_NOPAGE;
> - }
> -out:
> - trace_dax_load_hole(inode, vmf, ret);
> - return ret;
> -}
> -
> static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
> sector_t sector, size_t size, struct page *to,
> unsigned long vaddr)
> @@ -938,6 +894,50 @@ int dax_pfn_mkwrite(struct vm_fault *vmf)
> }
> EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
>
> +/*
> + * The user has performed a load from a hole in the file. Allocating
> + * a new page in the file would cause excessive storage usage for
> + * workloads with sparse files. We allocate a page cache page instead.
> + * We'll kick it out of the page cache if it's ever written to,
> + * otherwise it will simply fall out of the page cache under memory
> + * pressure without ever having been dirtied.
> + */
> +static int dax_load_hole(struct address_space *mapping, void **entry,
> + struct vm_fault *vmf)
> +{
> + struct inode *inode = mapping->host;
> + struct page *page;
> + int ret;
> +
> + /* Hole page already exists? Return it... */
> + if (!radix_tree_exceptional_entry(*entry)) {
> + page = *entry;
> + goto finish_fault;
> + }
> +
> + /* This will replace locked radix tree entry with a hole page */
> + page = find_or_create_page(mapping, vmf->pgoff,
> + vmf->gfp_mask | __GFP_ZERO);
> + if (!page) {
> + ret = VM_FAULT_OOM;
> + goto out;
> + }
> +
> +finish_fault:
> + vmf->page = page;
> + ret = finish_fault(vmf);
> + vmf->page = NULL;
> + *entry = page;
> + if (!ret) {
> + /* Grab reference for PTE that is now referencing the page */
> + get_page(page);
> + ret = VM_FAULT_NOPAGE;
> + }
> +out:
> + trace_dax_load_hole(inode, vmf, ret);
> + return ret;
> +}
> +
> static bool dax_range_is_aligned(struct block_device *bdev,
> unsigned int offset, unsigned int length)
> {
> --
> 2.9.4
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR