[PATCH] mm, fs: introduce mapping_gfp_constraint

From: Michal Hocko
Date: Fri Oct 02 2015 - 03:57:16 EST

There are many places which use mapping_gfp_mask to restrict a more
generic gfp mask which would be used for allocations which are not
directly related to the page cache but they are performed in the same
context.
Let's introduce a helper function which makes the restriction explicit
and easier to track. This patch doesn't introduce any functional
changes.

Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
drivers/gpu/drm/drm_gem.c | 2 +-
drivers/gpu/drm/i915/i915_gem.c | 3 +--
fs/btrfs/compression.c | 3 +--
fs/btrfs/ctree.h | 2 +-
fs/btrfs/free-space-cache.c | 4 ++--
fs/buffer.c | 2 +-
fs/ceph/addr.c | 7 ++++---
fs/cifs/file.c | 2 +-
fs/ext4/inode.c | 2 +-
fs/ext4/readpage.c | 2 +-
fs/logfs/segment.c | 2 +-
fs/mpage.c | 4 ++--
fs/namei.c | 2 +-
fs/nilfs2/inode.c | 4 ++--
fs/ntfs/file.c | 2 +-
fs/splice.c | 2 +-
include/linux/pagemap.h | 7 +++++++
mm/filemap.c | 4 ++--
mm/readahead.c | 4 ++--
19 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 3c2d4abd71c5..1d47d2e9487c 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -491,7 +491,7 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj)
* __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping)
* so shmem can relocate pages during swapin if required.
*/
- BUG_ON((mapping_gfp_mask(mapping) & __GFP_DMA32) &&
+ BUG_ON(mapping_gfp_constraint(mapping, __GFP_DMA32) &&
(page_to_pfn(p) >= 0x00100000UL));
}

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 249c2829bb41..f1d670f09032 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2216,9 +2216,8 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
* Fail silently without starting the shrinker
*/
mapping = file_inode(obj->base.filp)->i_mapping;
- gfp = mapping_gfp_mask(mapping);
+ gfp = mapping_gfp_constraint(mapping, ~(__GFP_IO | __GFP_RECLAIM));
gfp |= __GFP_NORETRY | __GFP_NOWARN;
- gfp &= ~(__GFP_IO | __GFP_RECLAIM);
sg = st->sgl;
st->nents = 0;
for (i = 0; i < page_count; i++) {
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 57ee8ca29b06..147a9761e47f 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -482,8 +482,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
goto next;
}

- page = __page_cache_alloc(mapping_gfp_mask(mapping) &
- ~__GFP_FS);
+ page = __page_cache_alloc(mapping_gfp_constraint(mapping, ~__GFP_FS));
if (!page)
break;

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 938efe33be80..eb90f0f1a124 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3316,7 +3316,7 @@ static inline bool btrfs_mixed_space_info(struct btrfs_space_info *space_info)

static inline gfp_t btrfs_alloc_write_mask(struct address_space *mapping)
{
- return mapping_gfp_mask(mapping) & ~__GFP_FS;
+ return mapping_gfp_constraint(mapping, ~__GFP_FS);
}

/* extent-tree.c */
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index abe3a66bd3ba..ed05da1b977e 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -85,8 +85,8 @@ static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
}

mapping_set_gfp_mask(inode->i_mapping,
- mapping_gfp_mask(inode->i_mapping) &
- ~(__GFP_FS | __GFP_HIGHMEM));
+ mapping_gfp_constraint(inode->i_mapping,
+ ~(__GFP_FS | __GFP_HIGHMEM)));

return inode;
}
diff --git a/fs/buffer.c b/fs/buffer.c
index 82283abb2795..51aff0296ce2 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -999,7 +999,7 @@ grow_dev_page(struct block_device *bdev, sector_t block,
int ret = 0; /* Will call free_more_memory() */
gfp_t gfp_mask;

- gfp_mask = (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS) | gfp;
+ gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp;

/*
* XXX: __getblk_slow() can not really deal with failure and
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 9d23e788d1df..b7d218a168fb 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1283,8 +1283,8 @@ static int ceph_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
int ret1;
struct address_space *mapping = inode->i_mapping;
struct page *page = find_or_create_page(mapping, 0,
- mapping_gfp_mask(mapping) &
- ~__GFP_FS);
+ mapping_gfp_constraint(mapping,
+ ~__GFP_FS));
if (!page) {
ret = VM_FAULT_OOM;
goto out;
@@ -1428,7 +1428,8 @@ void ceph_fill_inline_data(struct inode *inode, struct page *locked_page,
if (i_size_read(inode) == 0)
return;
page = find_or_create_page(mapping, 0,
- mapping_gfp_mask(mapping) & ~__GFP_FS);
+ mapping_gfp_constraint(mapping,
+ ~__GFP_FS));
if (!page)
return;
if (PageUptodate(page)) {
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 5cf50653796a..2d319e66b8f8 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3380,7 +3380,7 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
struct page *page, *tpage;
unsigned int expected_index;
int rc;
- gfp_t gfp = GFP_KERNEL & mapping_gfp_mask(mapping);
+ gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);

INIT_LIST_HEAD(tmplist);

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 612fbcf76b5c..60aaecd5598b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3344,7 +3344,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
int err = 0;

page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
- mapping_gfp_mask(mapping) & ~__GFP_FS);
+ mapping_gfp_constraint(mapping, ~__GFP_FS));
if (!page)
return -ENOMEM;

diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index c31d64d70cc0..1ac204caafe3 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -167,7 +167,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping,
page->index,
- GFP_KERNEL & mapping_gfp_mask(mapping)))
+ mapping_gfp_constraint(mapping, GFP_KERNEL)))
goto next_page;
}

diff --git a/fs/logfs/segment.c b/fs/logfs/segment.c
index 7f9b096d8d57..6de0fbfc6c00 100644
--- a/fs/logfs/segment.c
+++ b/fs/logfs/segment.c
@@ -57,7 +57,7 @@ static struct page *get_mapping_page(struct super_block *sb, pgoff_t index,
filler_t *filler = super->s_devops->readpage;
struct page *page;

- BUG_ON(mapping_gfp_mask(mapping) & __GFP_FS);
+ BUG_ON(mapping_gfp_constraint(mapping, __GFP_FS));
if (use_filler)
page = read_cache_page(mapping, index, filler, sb);
else {
diff --git a/fs/mpage.c b/fs/mpage.c
index 09abba7653aa..1480d3a18037 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -361,7 +361,7 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
sector_t last_block_in_bio = 0;
struct buffer_head map_bh;
unsigned long first_logical_block = 0;
- gfp_t gfp = GFP_KERNEL & mapping_gfp_mask(mapping);
+ gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);

map_bh.b_state = 0;
map_bh.b_size = 0;
@@ -397,7 +397,7 @@ int mpage_readpage(struct page *page, get_block_t get_block)
sector_t last_block_in_bio = 0;
struct buffer_head map_bh;
unsigned long first_logical_block = 0;
- gfp_t gfp = GFP_KERNEL & mapping_gfp_mask(page->mapping);
+ gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);

map_bh.b_state = 0;
map_bh.b_size = 0;
diff --git a/fs/namei.c b/fs/namei.c
index b090c4f44956..7bbc5e9611bb 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4677,7 +4677,7 @@ EXPORT_SYMBOL(__page_symlink);
int page_symlink(struct inode *inode, const char *symname, int len)
{
return __page_symlink(inode, symname, len,
- !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
+ !mapping_gfp_constraint(inode->i_mapping, __GFP_FS));
}
EXPORT_SYMBOL(page_symlink);

diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 4a73d6dffabf..b2ee592d48d2 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -356,7 +356,7 @@ struct inode *nilfs_new_inode(struct inode *dir, umode_t mode)
goto failed;

mapping_set_gfp_mask(inode->i_mapping,
- mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
+ mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS));

root = NILFS_I(dir)->i_root;
ii = NILFS_I(inode);
@@ -522,7 +522,7 @@ static int __nilfs_read_inode(struct super_block *sb,
up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
nilfs_set_inode_flags(inode);
mapping_set_gfp_mask(inode->i_mapping,
- mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
+ mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS));
return 0;

failed_unmap:
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 262561fea923..916e3efeaa0e 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -526,7 +526,7 @@ static inline int __ntfs_grab_cache_pages(struct address_space *mapping,
}
err = add_to_page_cache_lru(*cached_page, mapping,
index,
- GFP_KERNEL & mapping_gfp_mask(mapping));
+ mapping_gfp_constraint(mapping, GFP_KERNEL));
if (unlikely(err)) {
if (err == -EEXIST)
continue;
diff --git a/fs/splice.c b/fs/splice.c
index 5fc1e50a7f30..9ce27b1e9690 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -360,7 +360,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
break;

error = add_to_page_cache_lru(page, mapping, index,
- GFP_KERNEL & mapping_gfp_mask(mapping));
+ mapping_gfp_constraint(mapping, GFP_KERNEL));
if (unlikely(error)) {
page_cache_release(page);
if (error == -EEXIST)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 3e95fb6a77af..df214a4b886d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -69,6 +69,13 @@ static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
}

+/* Restricts the given gfp_mask to what the mapping allows. */
+static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
+ gfp_t gfp_mask)
+{
+ return mapping_gfp_mask(mapping) & gfp_mask;
+}
+
/*
* This is non-atomic. Only to be used before the mapping is activated.
* Probably needs a barrier...
diff --git a/mm/filemap.c b/mm/filemap.c
index 972251764243..f86aba253950 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1725,7 +1725,7 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
goto out;
}
error = add_to_page_cache_lru(page, mapping, index,
- GFP_KERNEL & mapping_gfp_mask(mapping));
+ mapping_gfp_constraint(mapping, GFP_KERNEL));
if (error) {
page_cache_release(page);
if (error == -EEXIST) {
@@ -1827,7 +1827,7 @@ static int page_cache_read(struct file *file, pgoff_t offset)
return -ENOMEM;

ret = add_to_page_cache_lru(page, mapping, offset,
- GFP_KERNEL & mapping_gfp_mask(mapping));
+ mapping_gfp_constraint(mapping, GFP_KERNEL));
if (ret == 0)
ret = mapping->a_ops->readpage(file, page);
else if (ret == -EEXIST)
diff --git a/mm/readahead.c b/mm/readahead.c
index 1ede8c0d3702..bd55f8384f5d 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -91,7 +91,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping,
page->index,
- GFP_KERNEL & mapping_gfp_mask(mapping))) {
+ mapping_gfp_constraint(mapping, GFP_KERNEL))) {
read_cache_pages_invalidate_page(mapping, page);
continue;
}
@@ -130,7 +130,7 @@ static int read_pages(struct address_space *mapping, struct file *filp,
list_del(&page->lru);
if (!add_to_page_cache_lru(page, mapping,
page->index,
- GFP_KERNEL & mapping_gfp_mask(mapping))) {
+ mapping_gfp_constraint(mapping, GFP_KERNEL))) {
mapping->a_ops->readpage(filp, page);
}
page_cache_release(page);
--
2.5.1


--
Michal Hocko
SUSE Labs
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