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, 11 insertions, 6 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index b2d10da505ef..264f6949511e 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -369,7 +369,8 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
  * Check if filesystem has nblocks free & available for allocation.
  * On success return 1, return 0 on failure.
  */
-static int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
+static int ext4_has_free_blocks(struct ext4_sb_info *sbi,
+                                s64 nblocks, unsigned int flags)
 {
         s64 free_blocks, dirty_blocks, root_blocks;
         struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
@@ -393,7 +394,9 @@ static int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
         /* Hm, nope.  Are (enough) root reserved blocks available? */
         if (sbi->s_resuid == current_fsuid() ||
             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
-            capable(CAP_SYS_RESOURCE)) {
+            capable(CAP_SYS_RESOURCE) ||
+                (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
+
                 if (free_blocks >= (nblocks + dirty_blocks))
                         return 1;
         }
@@ -402,9 +405,9 @@ static int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
 }
 
 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
-                                                s64 nblocks)
+                           s64 nblocks, unsigned int flags)
 {
-        if (ext4_has_free_blocks(sbi, nblocks)) {
+        if (ext4_has_free_blocks(sbi, nblocks, flags)) {
                 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
                 return 0;
         } else
@@ -425,7 +428,7 @@ int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
  */
 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 {
-        if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
+        if (!ext4_has_free_blocks(EXT4_SB(sb), 1, 0) ||
             (*retries)++ > 3 ||
             !EXT4_SB(sb)->s_journal)
                 return 0;
@@ -448,7 +451,8 @@ int ext4_should_retry_alloc(struct super_block *sb, int *retries)
  * error stores in errp pointer
  */
 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
-                ext4_fsblk_t goal, unsigned long *count, int *errp)
+                                  ext4_fsblk_t goal, unsigned int flags,
+                                  unsigned long *count, int *errp)
 {
         struct ext4_allocation_request ar;
         ext4_fsblk_t ret;
@@ -458,6 +462,7 @@ ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
         ar.inode = inode;
         ar.goal = goal;
         ar.len = count ? *count : 1;
+        ar.flags = flags;
 
         ret = ext4_mb_new_blocks(handle, &ar, errp);
         if (count)