[PATCH 02/12] fs: kill BDI_CAP_SWAP_BACKED

Christoph Hellwig
2015-01-08T17:45:23Z

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 <hch@lst.de>
---
include/linux/backing-dev.h | 13 -------------
mm/madvise.c | 19 +++++++++++--------
mm/shmem.c | 25 +++++++------------------
mm/swap.c | 2 --
mm/swap_state.c | 7 +------
5 files changed, 19 insertions(+), 47 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..073b41a 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