ext4: add flag to ext4_has_free_blocks

This patch adds an allocation request flag to the ext4_has_free_blocks
function which enables the use of reserved blocks.  This will allow a
punch hole to proceed even if the disk is full.  Punching a hole may
require additional blocks to first split the extents.

Because ext4_has_free_blocks is a low level function, the flag needs
to be passed down through several functions listed below:

ext4_ext_insert_extent
ext4_ext_create_new_leaf
ext4_ext_grow_indepth
ext4_ext_split
ext4_ext_new_meta_block
ext4_mb_new_blocks
ext4_claim_free_blocks
ext4_has_free_blocks

[ext4 punch hole patch series 1/5 v7]

Signed-off-by: Allison Henderson <achender@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Mingming Cao <cmm@us.ibm.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 396b01f5c4fb..859f2ae8864e 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4236,7 +4236,9 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
                  * there is enough free blocks to do block allocation
                  * and verify allocation doesn't exceed the quota limits.
                  */
-                while (ar->len && ext4_claim_free_blocks(sbi, ar->len)) {
+                while (ar->len &&
+                        ext4_claim_free_blocks(sbi, ar->len, ar->flags)) {
+
                         /* let others to free the space */
                         yield();
                         ar->len = ar->len >> 1;
@@ -4246,9 +4248,15 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
                         return 0;
                 }
                 reserv_blks = ar->len;
-                while (ar->len && dquot_alloc_block(ar->inode, ar->len)) {
-                        ar->flags |= EXT4_MB_HINT_NOPREALLOC;
-                        ar->len--;
+                if (ar->flags & EXT4_MB_USE_ROOT_BLOCKS) {
+                        dquot_alloc_block_nofail(ar->inode, ar->len);
+                } else {
+                        while (ar->len &&
+                                dquot_alloc_block(ar->inode, ar->len)) {
+
+                                ar->flags |= EXT4_MB_HINT_NOPREALLOC;
+                                ar->len--;
+                        }
                 }
                 inquota = ar->len;
                 if (ar->len == 0) {