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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2009-01-05 21:46:55 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-01-05 21:46:55 -0500
commit8556e8f3b6c4c11601ce1e9ea8090a6d8bd5daae (patch)
tree8a0da99a4781cbde8c050d7cbcd85f31fd54e894
parent648f5879f5892dddd3ba71cd0d285599f40f2512 (diff)
ext4: Don't allow new groups to be added during block allocation
After we mark the blocks in the buddy cache as allocated, we need to ensure that we don't reinit the buddy cache until the block bitmap is updated. This commit achieves this by holding the group_info alloc_semaphore till ext4_mb_release_context Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
-rw-r--r--fs/ext4/mballoc.c16
-rw-r--r--fs/ext4/mballoc.h5
2 files changed, 18 insertions, 3 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 7d7f6f91d555..0c7e247f714c 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1052,7 +1052,8 @@ static void ext4_mb_release_desc(struct ext4_buddy *e4b)
if (e4b->bd_buddy_page)
page_cache_release(e4b->bd_buddy_page);
/* Done with the buddy cache */
- up_read(e4b->alloc_semp);
+ if (e4b->alloc_semp)
+ up_read(e4b->alloc_semp);
}
@@ -1371,7 +1372,9 @@ static void ext4_mb_use_best_found(struct ext4_allocation_context *ac,
get_page(ac->ac_bitmap_page);
ac->ac_buddy_page = e4b->bd_buddy_page;
get_page(ac->ac_buddy_page);
-
+ /* on allocation we use ac to track the held semaphore */
+ ac->alloc_semp = e4b->alloc_semp;
+ e4b->alloc_semp = NULL;
/* store last allocated for subsequent stream allocation */
if ((ac->ac_flags & EXT4_MB_HINT_DATA)) {
spin_lock(&sbi->s_md_lock);
@@ -4289,6 +4292,7 @@ ext4_mb_initialize_context(struct ext4_allocation_context *ac,
ac->ac_pa = NULL;
ac->ac_bitmap_page = NULL;
ac->ac_buddy_page = NULL;
+ ac->alloc_semp = NULL;
ac->ac_lg = NULL;
/* we have to define context: we'll we work with a file or
@@ -4469,6 +4473,8 @@ static int ext4_mb_release_context(struct ext4_allocation_context *ac)
}
ext4_mb_put_pa(ac, ac->ac_sb, pa);
}
+ if (ac->alloc_semp)
+ up_read(ac->alloc_semp);
if (ac->ac_bitmap_page)
page_cache_release(ac->ac_bitmap_page);
if (ac->ac_buddy_page)
@@ -4569,10 +4575,14 @@ repeat:
ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len)
ext4_mb_new_preallocation(ac);
}
-
if (likely(ac->ac_status == AC_STATUS_FOUND)) {
*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_blks);
if (*errp == -EAGAIN) {
+ /*
+ * drop the reference that we took
+ * in ext4_mb_use_best_found
+ */
+ ext4_mb_release_context(ac);
ac->ac_b_ex.fe_group = 0;
ac->ac_b_ex.fe_start = 0;
ac->ac_b_ex.fe_len = 0;
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 95d4c7f29a8a..10a2921baf14 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -195,6 +195,11 @@ struct ext4_allocation_context {
__u8 ac_op; /* operation, for history only */
struct page *ac_bitmap_page;
struct page *ac_buddy_page;
+ /*
+ * pointer to the held semaphore upon successful
+ * block allocation
+ */
+ struct rw_semaphore *alloc_semp;
struct ext4_prealloc_space *ac_pa;
struct ext4_locality_group *ac_lg;
};