[PATCH V20 01/19] Btrfs: subpage-blocksize: Fix whole page read.
For the subpage-blocksize scenario, a page can contain multiple
blocks. In such cases, this patch handles reading data from files.
To track the status of individual blocks of a page, this patch makes use
of a bitmap pointed to by the newly introduced per-page 'struct
btrfs_page_private'.
The per-page btrfs_page_private->io_lock plays the same role as
BH_Uptodate_Lock (see end_buffer_async_read()) i.e. without the io_lock
we may end up in the following situation,
NOTE: Assume 64k page size and 4k block size. Also assume that the first
12 blocks of the page are contiguous while the next 4 blocks are
contiguous. When reading the page we end up submitting two "logical
address space" bios. So end_bio_extent_readpage function is invoked
twice, once for each bio.
|-+-+-|
| Task A | Task B | Task C |
|-+-+-|
| end_bio_extent_readpage | | |
| process block 0 | | |
| - clear BLK_STATE_IO| | |
| - page_read_complete| | |
| process block 1 | | |
| | | |
| | | |
| | end_bio_extent_readpage | |
| | process block 0 | |
| | - clear BLK_STATE_IO| |
| | - page_read_complete| |
| | process block 1 | |
| | | |
| process block 11| process block 3 | |
| - clear BLK_STATE_IO| - clear BLK_STATE_IO| |
| - page_read_complete| - page_read_complete| |
| - returns true| - returns true| |
| - unlock_page() | | |
| | | lock_page() |
| | - unlock_page() | |
|-+-+-|
We end up incorrectly unlocking the page twice and "Task C" ends up
working on an unlocked page. So private->io_lock makes sure that only
one of the tasks gets "true" as the return value when page_io_complete()
is invoked. As an optimization the patch gets the io_lock only when the
last block of the bio_vec is being processed.
Signed-off-by: Chandan Rajendra
---
fs/btrfs/extent_io.c | 371 ---
fs/btrfs/extent_io.h | 74 +-
fs/btrfs/inode.c | 16 +--
3 files changed, 338 insertions(+), 123 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index e197d47..a349f99 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -24,6 +24,7 @@
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
+static struct kmem_cache *page_private_cache;
static struct bio_set *btrfs_bioset;
static inline bool extent_state_in_tree(const struct extent_state *state)
@@ -174,10 +175,16 @@ int __init extent_io_init(void)
if (!extent_buffer_cache)
goto free_state_cache;
+ page_private_cache = kmem_cache_create("btrfs_page_private",
+ sizeof(struct btrfs_page_private), 0,
+ SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
+ if (!page_private_cache)
+ goto free_buffer_cache;
+
btrfs_bioset = bioset_create(BIO_POOL_SIZE,
offsetof(struct btrfs_io_bio, bio));
if (!btrfs_bioset)
- goto free_buffer_cache;
+ goto free_page_private_cache;
if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
goto free_bioset;
@@ -188,6 +195,10 @@ free_bioset:
bioset_free(btrfs_bioset);
btrfs_bioset = NULL;
+free_page_private_cache:
+ kmem_cache_destroy(page_private_cache);
+ page_private_cache = NULL;
+
free_buffer_cache:
kmem_cache_destroy(extent_buffer_cache);
extent_buffer_cache = NULL;
@@ -1323,6 +1334,95 @@ int clear_record_extent_bits(struct extent_io_tree
*tree, u64 start, u64 end,
changeset);
}
+static int modify_page_blks_state(struct page *page,
+ unsigned long blk_states,
+ u64 start, u64 end, int set)
+{
+ struct inode *inode = page->mapping->host;
+ unsigned long *bitmap;
+ unsigned long first_state;
+ unsigned long state;
+ u64 nr_blks;
+ u64 blk;
+
+ ASSERT(BTRFS_I(ino
Re: [PATCH V20 01/19] Btrfs: subpage-blocksize: Fix whole page read.
On 07/04/2016 12:34 AM, Chandan Rajendra wrote:
For the subpage-blocksize scenario, a page can contain multiple
blocks. In such cases, this patch handles reading data from files.
To track the status of individual blocks of a page, this patch makes use
of a bitmap pointed to by the newly introduced per-page 'struct
btrfs_page_private'.
The per-page btrfs_page_private->io_lock plays the same role as
BH_Uptodate_Lock (see end_buffer_async_read()) i.e. without the io_lock
we may end up in the following situation,
NOTE: Assume 64k page size and 4k block size. Also assume that the first
12 blocks of the page are contiguous while the next 4 blocks are
contiguous. When reading the page we end up submitting two "logical
address space" bios. So end_bio_extent_readpage function is invoked
twice, once for each bio.
|-+-+-|
| Task A | Task B | Task C |
|-+-+-|
| end_bio_extent_readpage | | |
| process block 0 | | |
| - clear BLK_STATE_IO| | |
| - page_read_complete| | |
| process block 1 | | |
| | | |
| | | |
| | end_bio_extent_readpage | |
| | process block 0 | |
| | - clear BLK_STATE_IO| |
| | - page_read_complete| |
| | process block 1 | |
| | | |
| process block 11| process block 3 | |
| - clear BLK_STATE_IO| - clear BLK_STATE_IO| |
| - page_read_complete| - page_read_complete| |
| - returns true| - returns true| |
| - unlock_page() | | |
| | | lock_page() |
| | - unlock_page() | |
|-+-+-|
We end up incorrectly unlocking the page twice and "Task C" ends up
working on an unlocked page. So private->io_lock makes sure that only
one of the tasks gets "true" as the return value when page_io_complete()
is invoked. As an optimization the patch gets the io_lock only when the
last block of the bio_vec is being processed.
Signed-off-by: Chandan Rajendra
---
fs/btrfs/extent_io.c | 371 ---
fs/btrfs/extent_io.h | 74 +-
fs/btrfs/inode.c | 16 +--
3 files changed, 338 insertions(+), 123 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index e197d47..a349f99 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -24,6 +24,7 @@
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
+static struct kmem_cache *page_private_cache;
static struct bio_set *btrfs_bioset;
static inline bool extent_state_in_tree(const struct extent_state *state)
@@ -174,10 +175,16 @@ int __init extent_io_init(void)
if (!extent_buffer_cache)
goto free_state_cache;
+ page_private_cache = kmem_cache_create("btrfs_page_private",
+ sizeof(struct btrfs_page_private), 0,
+ SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
+ if (!page_private_cache)
+ goto free_buffer_cache;
+
btrfs_bioset = bioset_create(BIO_POOL_SIZE,
offsetof(struct btrfs_io_bio, bio));
if (!btrfs_bioset)
- goto free_buffer_cache;
+ goto free_page_private_cache;
if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
goto free_bioset;
@@ -188,6 +195,10 @@ free_bioset:
bioset_free(btrfs_bioset);
btrfs_bioset = NULL;
+free_page_private_cache:
+ kmem_cache_destroy(page_private_cache);
+ page_private_cache = NULL;
+
free_buffer_cache:
kmem_cache_destroy(extent_buffer_cache);
extent_buffer_cache = NULL;
@@ -1323,6 +1334,95 @@ int clear_record_extent_bits(struct extent_io_tree
*tree, u64 start, u64 end,
changeset);
}
+static int modify_page_blks_state(struct page *page,
+ unsigned long blk_states,
+ u64 start, u64 end, int set)
+{
+ struct inode *inode = page->mapping->host;
+ unsigned long *bitmap;
+ unsigned long first_state;
+ unsigned long state;
+ u64 nr_blks;
+
Re: [PATCH V20 01/19] Btrfs: subpage-blocksize: Fix whole page read.
On Tuesday, July 26, 2016 12:11:49 PM Josef Bacik wrote:
> On 07/04/2016 12:34 AM, Chandan Rajendra wrote:
> > For the subpage-blocksize scenario, a page can contain multiple
> > blocks. In such cases, this patch handles reading data from files.
> >
> > To track the status of individual blocks of a page, this patch makes use
> > of a bitmap pointed to by the newly introduced per-page 'struct
> > btrfs_page_private'.
> >
> > The per-page btrfs_page_private->io_lock plays the same role as
> > BH_Uptodate_Lock (see end_buffer_async_read()) i.e. without the io_lock
> > we may end up in the following situation,
> >
> > NOTE: Assume 64k page size and 4k block size. Also assume that the first
> > 12 blocks of the page are contiguous while the next 4 blocks are
> > contiguous. When reading the page we end up submitting two "logical
> > address space" bios. So end_bio_extent_readpage function is invoked
> > twice, once for each bio.
> >
> > |-+-+-|
> > | Task A | Task B | Task C |
> > |-+-+-|
> > | end_bio_extent_readpage | | |
> > | process block 0 | | |
> > | - clear BLK_STATE_IO| | |
> > | - page_read_complete| | |
> > | process block 1 | | |
> > | | | |
> > | | | |
> > | | end_bio_extent_readpage | |
> > | | process block 0 | |
> > | | - clear BLK_STATE_IO| |
> > | | - page_read_complete| |
> > | | process block 1 | |
> > | | | |
> > | process block 11| process block 3 | |
> > | - clear BLK_STATE_IO| - clear BLK_STATE_IO| |
> > | - page_read_complete| - page_read_complete| |
> > | - returns true| - returns true| |
> > | - unlock_page() | | |
> > | | | lock_page() |
> > | | - unlock_page() | |
> > |-+-+-|
> >
> > We end up incorrectly unlocking the page twice and "Task C" ends up
> > working on an unlocked page. So private->io_lock makes sure that only
> > one of the tasks gets "true" as the return value when page_io_complete()
> > is invoked. As an optimization the patch gets the io_lock only when the
> > last block of the bio_vec is being processed.
> >
> > Signed-off-by: Chandan Rajendra
> > ---
> > fs/btrfs/extent_io.c | 371
> > ---
> > fs/btrfs/extent_io.h | 74 +-
> > fs/btrfs/inode.c | 16 +--
> > 3 files changed, 338 insertions(+), 123 deletions(-)
> >
> > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> > index e197d47..a349f99 100644
> > --- a/fs/btrfs/extent_io.c
> > +++ b/fs/btrfs/extent_io.c
> > @@ -24,6 +24,7 @@
> >
> > static struct kmem_cache *extent_state_cache;
> > static struct kmem_cache *extent_buffer_cache;
> > +static struct kmem_cache *page_private_cache;
> > static struct bio_set *btrfs_bioset;
> >
> > static inline bool extent_state_in_tree(const struct extent_state *state)
> > @@ -174,10 +175,16 @@ int __init extent_io_init(void)
> > if (!extent_buffer_cache)
> > goto free_state_cache;
> >
> > + page_private_cache = kmem_cache_create("btrfs_page_private",
> > + sizeof(struct btrfs_page_private), 0,
> > + SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
> > + if (!page_private_cache)
> > + goto free_buffer_cache;
> > +
> > btrfs_bioset = bioset_create(BIO_POOL_SIZE,
> > offsetof(struct btrfs_io_bio, bio));
> > if (!btrfs_bioset)
> > - goto free_buffer_cache;
> > + goto free_page_private_cache;
> >
> > if (bioset_integrity_create(btrfs_bioset, BIO_POOL_SIZE))
> > goto free_bioset;
> > @@ -188,6 +195,10 @@ free_bioset:
> > bioset_free(btrfs_bioset);
> > btrfs_bioset = NULL;
> >
> > +free_page_private_cache:
> > + kmem_cache_destroy(page_private_cache);
> > + page_private_cache = NULL;
> > +
> > free_buffer_cache:
> > kmem_cache_destroy(extent_buffer_cache);
> > extent_buffer_cache = NULL;
> > @@ -1323,6 +1334,95 @@ int clear_record_extent_bits(struct extent_io_tree
> > *tree, u64 start, u64 end,
> >
