On Wed 14-01-15 10:42:31, Christoph Hellwig wrote:
> This bdi flag isn't too useful - we can determine that a vma is backed by
> either swap or shmem trivially in the caller.
>
> This also allows removing the backing_dev_info instaces for swap and shmem
> in favor of noop_backing_dev_info.
>
> Signed-off-by: Christoph Hellwig <h...@lst.de>
> Reviewed-by: Tejun Heo <t...@kernel.org>
Looks good to me. You can add:
Reviewed-by: Jan Kara <j...@suse.cz>
Honza
> ---
> include/linux/backing-dev.h | 13 -------------
> mm/madvise.c | 17 ++++++++++-------
> mm/shmem.c | 25 +++++++------------------
> mm/swap.c | 2 --
> mm/swap_state.c | 7 +------
> 5 files changed, 18 insertions(+), 46 deletions(-)
>
> diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
> index 5da6012..e936cea 100644
> --- a/include/linux/backing-dev.h
> +++ b/include/linux/backing-dev.h
> @@ -238,8 +238,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi,
> unsigned int max_ratio);
> * BDI_CAP_WRITE_MAP: Can be mapped for writing
> * BDI_CAP_EXEC_MAP: Can be mapped for execution
> *
> - * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
> - *
> * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
> */
> #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
> @@ -250,7 +248,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi,
> unsigned int max_ratio);
> #define BDI_CAP_WRITE_MAP 0x00000020
> #define BDI_CAP_EXEC_MAP 0x00000040
> #define BDI_CAP_NO_ACCT_WB 0x00000080
> -#define BDI_CAP_SWAP_BACKED 0x00000100
> #define BDI_CAP_STABLE_WRITES 0x00000200
> #define BDI_CAP_STRICTLIMIT 0x00000400
>
> @@ -329,11 +326,6 @@ static inline bool bdi_cap_account_writeback(struct
> backing_dev_info *bdi)
> BDI_CAP_NO_WRITEBACK));
> }
>
> -static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
> -{
> - return bdi->capabilities & BDI_CAP_SWAP_BACKED;
> -}
> -
> static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
> {
> return bdi_cap_writeback_dirty(mapping->backing_dev_info);
> @@ -344,11 +336,6 @@ static inline bool mapping_cap_account_dirty(struct
> address_space *mapping)
> return bdi_cap_account_dirty(mapping->backing_dev_info);
> }
>
> -static inline bool mapping_cap_swap_backed(struct address_space *mapping)
> -{
> - return bdi_cap_swap_backed(mapping->backing_dev_info);
> -}
> -
> static inline int bdi_sched_wait(void *word)
> {
> schedule();
> diff --git a/mm/madvise.c b/mm/madvise.c
> index a271adc..1383a89 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -222,19 +222,22 @@ static long madvise_willneed(struct vm_area_struct *vma,
> struct file *file = vma->vm_file;
>
> #ifdef CONFIG_SWAP
> - if (!file || mapping_cap_swap_backed(file->f_mapping)) {
> + if (!file) {
> *prev = vma;
> - if (!file)
> - force_swapin_readahead(vma, start, end);
> - else
> - force_shm_swapin_readahead(vma, start, end,
> - file->f_mapping);
> + force_swapin_readahead(vma, start, end);
> return 0;
> }
> -#endif
>
> + if (shmem_mapping(file->f_mapping)) {
> + *prev = vma;
> + force_shm_swapin_readahead(vma, start, end,
> + file->f_mapping);
> + return 0;
> + }
> +#else
> if (!file)
> return -EBADF;
> +#endif
>
> if (file->f_mapping->a_ops->get_xip_mem) {
> /* no bad return value, but ignore advice */
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 73ba1df..1b77eaf 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -191,11 +191,6 @@ static const struct inode_operations
> shmem_dir_inode_operations;
> static const struct inode_operations shmem_special_inode_operations;
> static const struct vm_operations_struct shmem_vm_ops;
>
> -static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
> - .ra_pages = 0, /* No readahead */
> - .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
> -};
> -
> static LIST_HEAD(shmem_swaplist);
> static DEFINE_MUTEX(shmem_swaplist_mutex);
>
> @@ -765,11 +760,11 @@ static int shmem_writepage(struct page *page, struct
> writeback_control *wbc)
> goto redirty;
>
> /*
> - * shmem_backing_dev_info's capabilities prevent regular writeback or
> - * sync from ever calling shmem_writepage; but a stacking filesystem
> - * might use ->writepage of its underlying filesystem, in which case
> - * tmpfs should write out to swap only in response to memory pressure,
> - * and not for the writeback threads or sync.
> + * Our capabilities prevent regular writeback or sync from ever calling
> + * shmem_writepage; but a stacking filesystem might use ->writepage of
> + * its underlying filesystem, in which case tmpfs should write out to
> + * swap only in response to memory pressure, and not for the writeback
> + * threads or sync.
> */
> if (!wbc->for_reclaim) {
> WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
> @@ -1415,7 +1410,7 @@ static struct inode *shmem_get_inode(struct super_block
> *sb, const struct inode
> inode->i_ino = get_next_ino();
> inode_init_owner(inode, dir, mode);
> inode->i_blocks = 0;
> - inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
> + inode->i_mapping->backing_dev_info = &noop_backing_dev_info;
> inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
> inode->i_generation = get_seconds();
> info = SHMEM_I(inode);
> @@ -1461,7 +1456,7 @@ static struct inode *shmem_get_inode(struct super_block
> *sb, const struct inode
>
> bool shmem_mapping(struct address_space *mapping)
> {
> - return mapping->backing_dev_info == &shmem_backing_dev_info;
> + return mapping->host->i_sb->s_op == &shmem_ops;
> }
>
> #ifdef CONFIG_TMPFS
> @@ -3226,10 +3221,6 @@ int __init shmem_init(void)
> if (shmem_inode_cachep)
> return 0;
>
> - error = bdi_init(&shmem_backing_dev_info);
> - if (error)
> - goto out4;
> -
> error = shmem_init_inodecache();
> if (error)
> goto out3;
> @@ -3253,8 +3244,6 @@ out1:
> out2:
> shmem_destroy_inodecache();
> out3:
> - bdi_destroy(&shmem_backing_dev_info);
> -out4:
> shm_mnt = ERR_PTR(error);
> return error;
> }
> diff --git a/mm/swap.c b/mm/swap.c
> index 8a12b33..4e0109a 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -1138,8 +1138,6 @@ void __init swap_setup(void)
> #ifdef CONFIG_SWAP
> int i;
>
> - if (bdi_init(swapper_spaces[0].backing_dev_info))
> - panic("Failed to init swap bdi");
> for (i = 0; i < MAX_SWAPFILES; i++) {
> spin_lock_init(&swapper_spaces[i].tree_lock);
> INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 9711342..1c137b6 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -32,17 +32,12 @@ static const struct address_space_operations swap_aops = {
> #endif
> };
>
> -static struct backing_dev_info swap_backing_dev_info = {
> - .name = "swap",
> - .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
> -};
> -
> struct address_space swapper_spaces[MAX_SWAPFILES] = {
> [0 ... MAX_SWAPFILES - 1] = {
> .page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
> .i_mmap_writable = ATOMIC_INIT(0),
> .a_ops = &swap_aops,
> - .backing_dev_info = &swap_backing_dev_info,
> + .backing_dev_info = &noop_backing_dev_info,
> }
> };
>
> --
> 1.9.1
>
> --
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--
Jan Kara <j...@suse.cz>
SUSE Labs, CR
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