linux/fs/btrfs/extent_map.c
Tejun Heo 5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00

419 lines
10 KiB
C

#include <linux/err.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include "extent_map.h"
static struct kmem_cache *extent_map_cache;
int __init extent_map_init(void)
{
extent_map_cache = kmem_cache_create("extent_map",
sizeof(struct extent_map), 0,
SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, NULL);
if (!extent_map_cache)
return -ENOMEM;
return 0;
}
void extent_map_exit(void)
{
if (extent_map_cache)
kmem_cache_destroy(extent_map_cache);
}
/**
* extent_map_tree_init - initialize extent map tree
* @tree: tree to initialize
* @mask: flags for memory allocations during tree operations
*
* Initialize the extent tree @tree. Should be called for each new inode
* or other user of the extent_map interface.
*/
void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
{
tree->map = RB_ROOT;
rwlock_init(&tree->lock);
}
/**
* alloc_extent_map - allocate new extent map structure
* @mask: memory allocation flags
*
* Allocate a new extent_map structure. The new structure is
* returned with a reference count of one and needs to be
* freed using free_extent_map()
*/
struct extent_map *alloc_extent_map(gfp_t mask)
{
struct extent_map *em;
em = kmem_cache_alloc(extent_map_cache, mask);
if (!em || IS_ERR(em))
return em;
em->in_tree = 0;
em->flags = 0;
atomic_set(&em->refs, 1);
return em;
}
/**
* free_extent_map - drop reference count of an extent_map
* @em: extent map beeing releasead
*
* Drops the reference out on @em by one and free the structure
* if the reference count hits zero.
*/
void free_extent_map(struct extent_map *em)
{
if (!em)
return;
WARN_ON(atomic_read(&em->refs) == 0);
if (atomic_dec_and_test(&em->refs)) {
WARN_ON(em->in_tree);
kmem_cache_free(extent_map_cache, em);
}
}
static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
struct rb_node *node)
{
struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;
struct extent_map *entry;
while (*p) {
parent = *p;
entry = rb_entry(parent, struct extent_map, rb_node);
WARN_ON(!entry->in_tree);
if (offset < entry->start)
p = &(*p)->rb_left;
else if (offset >= extent_map_end(entry))
p = &(*p)->rb_right;
else
return parent;
}
entry = rb_entry(node, struct extent_map, rb_node);
entry->in_tree = 1;
rb_link_node(node, parent, p);
rb_insert_color(node, root);
return NULL;
}
/*
* search through the tree for an extent_map with a given offset. If
* it can't be found, try to find some neighboring extents
*/
static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
struct rb_node **prev_ret,
struct rb_node **next_ret)
{
struct rb_node *n = root->rb_node;
struct rb_node *prev = NULL;
struct rb_node *orig_prev = NULL;
struct extent_map *entry;
struct extent_map *prev_entry = NULL;
while (n) {
entry = rb_entry(n, struct extent_map, rb_node);
prev = n;
prev_entry = entry;
WARN_ON(!entry->in_tree);
if (offset < entry->start)
n = n->rb_left;
else if (offset >= extent_map_end(entry))
n = n->rb_right;
else
return n;
}
if (prev_ret) {
orig_prev = prev;
while (prev && offset >= extent_map_end(prev_entry)) {
prev = rb_next(prev);
prev_entry = rb_entry(prev, struct extent_map, rb_node);
}
*prev_ret = prev;
prev = orig_prev;
}
if (next_ret) {
prev_entry = rb_entry(prev, struct extent_map, rb_node);
while (prev && offset < prev_entry->start) {
prev = rb_prev(prev);
prev_entry = rb_entry(prev, struct extent_map, rb_node);
}
*next_ret = prev;
}
return NULL;
}
/* check to see if two extent_map structs are adjacent and safe to merge */
static int mergable_maps(struct extent_map *prev, struct extent_map *next)
{
if (test_bit(EXTENT_FLAG_PINNED, &prev->flags))
return 0;
/*
* don't merge compressed extents, we need to know their
* actual size
*/
if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
return 0;
if (extent_map_end(prev) == next->start &&
prev->flags == next->flags &&
prev->bdev == next->bdev &&
((next->block_start == EXTENT_MAP_HOLE &&
prev->block_start == EXTENT_MAP_HOLE) ||
(next->block_start == EXTENT_MAP_INLINE &&
prev->block_start == EXTENT_MAP_INLINE) ||
(next->block_start == EXTENT_MAP_DELALLOC &&
prev->block_start == EXTENT_MAP_DELALLOC) ||
(next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
next->block_start == extent_map_block_end(prev)))) {
return 1;
}
return 0;
}
int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
{
int ret = 0;
struct extent_map *merge = NULL;
struct rb_node *rb;
struct extent_map *em;
write_lock(&tree->lock);
em = lookup_extent_mapping(tree, start, len);
WARN_ON(!em || em->start != start);
if (!em)
goto out;
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
if (em->start != 0) {
rb = rb_prev(&em->rb_node);
if (rb)
merge = rb_entry(rb, struct extent_map, rb_node);
if (rb && mergable_maps(merge, em)) {
em->start = merge->start;
em->len += merge->len;
em->block_len += merge->block_len;
em->block_start = merge->block_start;
merge->in_tree = 0;
rb_erase(&merge->rb_node, &tree->map);
free_extent_map(merge);
}
}
rb = rb_next(&em->rb_node);
if (rb)
merge = rb_entry(rb, struct extent_map, rb_node);
if (rb && mergable_maps(em, merge)) {
em->len += merge->len;
em->block_len += merge->len;
rb_erase(&merge->rb_node, &tree->map);
merge->in_tree = 0;
free_extent_map(merge);
}
free_extent_map(em);
out:
write_unlock(&tree->lock);
return ret;
}
/**
* add_extent_mapping - add new extent map to the extent tree
* @tree: tree to insert new map in
* @em: map to insert
*
* Insert @em into @tree or perform a simple forward/backward merge with
* existing mappings. The extent_map struct passed in will be inserted
* into the tree directly, with an additional reference taken, or a
* reference dropped if the merge attempt was successfull.
*/
int add_extent_mapping(struct extent_map_tree *tree,
struct extent_map *em)
{
int ret = 0;
struct extent_map *merge = NULL;
struct rb_node *rb;
struct extent_map *exist;
exist = lookup_extent_mapping(tree, em->start, em->len);
if (exist) {
free_extent_map(exist);
ret = -EEXIST;
goto out;
}
rb = tree_insert(&tree->map, em->start, &em->rb_node);
if (rb) {
ret = -EEXIST;
goto out;
}
atomic_inc(&em->refs);
if (em->start != 0) {
rb = rb_prev(&em->rb_node);
if (rb)
merge = rb_entry(rb, struct extent_map, rb_node);
if (rb && mergable_maps(merge, em)) {
em->start = merge->start;
em->len += merge->len;
em->block_len += merge->block_len;
em->block_start = merge->block_start;
merge->in_tree = 0;
rb_erase(&merge->rb_node, &tree->map);
free_extent_map(merge);
}
}
rb = rb_next(&em->rb_node);
if (rb)
merge = rb_entry(rb, struct extent_map, rb_node);
if (rb && mergable_maps(em, merge)) {
em->len += merge->len;
em->block_len += merge->len;
rb_erase(&merge->rb_node, &tree->map);
merge->in_tree = 0;
free_extent_map(merge);
}
out:
return ret;
}
/* simple helper to do math around the end of an extent, handling wrap */
static u64 range_end(u64 start, u64 len)
{
if (start + len < start)
return (u64)-1;
return start + len;
}
/**
* lookup_extent_mapping - lookup extent_map
* @tree: tree to lookup in
* @start: byte offset to start the search
* @len: length of the lookup range
*
* Find and return the first extent_map struct in @tree that intersects the
* [start, len] range. There may be additional objects in the tree that
* intersect, so check the object returned carefully to make sure that no
* additional lookups are needed.
*/
struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
u64 start, u64 len)
{
struct extent_map *em;
struct rb_node *rb_node;
struct rb_node *prev = NULL;
struct rb_node *next = NULL;
u64 end = range_end(start, len);
rb_node = __tree_search(&tree->map, start, &prev, &next);
if (!rb_node && prev) {
em = rb_entry(prev, struct extent_map, rb_node);
if (end > em->start && start < extent_map_end(em))
goto found;
}
if (!rb_node && next) {
em = rb_entry(next, struct extent_map, rb_node);
if (end > em->start && start < extent_map_end(em))
goto found;
}
if (!rb_node) {
em = NULL;
goto out;
}
if (IS_ERR(rb_node)) {
em = ERR_PTR(PTR_ERR(rb_node));
goto out;
}
em = rb_entry(rb_node, struct extent_map, rb_node);
if (end > em->start && start < extent_map_end(em))
goto found;
em = NULL;
goto out;
found:
atomic_inc(&em->refs);
out:
return em;
}
/**
* search_extent_mapping - find a nearby extent map
* @tree: tree to lookup in
* @start: byte offset to start the search
* @len: length of the lookup range
*
* Find and return the first extent_map struct in @tree that intersects the
* [start, len] range.
*
* If one can't be found, any nearby extent may be returned
*/
struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
u64 start, u64 len)
{
struct extent_map *em;
struct rb_node *rb_node;
struct rb_node *prev = NULL;
struct rb_node *next = NULL;
rb_node = __tree_search(&tree->map, start, &prev, &next);
if (!rb_node && prev) {
em = rb_entry(prev, struct extent_map, rb_node);
goto found;
}
if (!rb_node && next) {
em = rb_entry(next, struct extent_map, rb_node);
goto found;
}
if (!rb_node) {
em = NULL;
goto out;
}
if (IS_ERR(rb_node)) {
em = ERR_PTR(PTR_ERR(rb_node));
goto out;
}
em = rb_entry(rb_node, struct extent_map, rb_node);
goto found;
em = NULL;
goto out;
found:
atomic_inc(&em->refs);
out:
return em;
}
/**
* remove_extent_mapping - removes an extent_map from the extent tree
* @tree: extent tree to remove from
* @em: extent map beeing removed
*
* Removes @em from @tree. No reference counts are dropped, and no checks
* are done to see if the range is in use
*/
int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
{
int ret = 0;
WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
rb_erase(&em->rb_node, &tree->map);
em->in_tree = 0;
return ret;
}