delay capable() check in ext4_has_free_blocks()
As reported by Eric Paris, the capable() check in ext4_has_free_blocks()
sometimes causes SELinux denials.
We can rearrange the logic so that we only try to use the root-reserved
blocks when necessary, and even then we can move the capable() test
to last, to avoid the check most of the time.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index e28203e..d2003cd 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -599,18 +599,13 @@
*/
int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
{
- s64 free_blocks, dirty_blocks;
- s64 root_blocks = 0;
+ s64 free_blocks, dirty_blocks, root_blocks;
struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
free_blocks = percpu_counter_read_positive(fbc);
dirty_blocks = percpu_counter_read_positive(dbc);
-
- if (!capable(CAP_SYS_RESOURCE) &&
- sbi->s_resuid != current->fsuid &&
- (sbi->s_resgid == 0 || !in_group_p(sbi->s_resgid)))
- root_blocks = ext4_r_blocks_count(sbi->s_es);
+ root_blocks = ext4_r_blocks_count(sbi->s_es);
if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
EXT4_FREEBLOCKS_WATERMARK) {
@@ -623,13 +618,20 @@
}
}
/* Check whether we have space after
- * accounting for current dirty blocks
+ * accounting for current dirty blocks & root reserved blocks.
*/
- if (free_blocks < ((root_blocks + nblocks) + dirty_blocks))
- /* we don't have free space */
- return 0;
+ if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
+ return 1;
- return 1;
+ /* 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)) {
+ if (free_blocks >= (nblocks + dirty_blocks))
+ return 1;
+ }
+
+ return 0;
}
int ext4_claim_free_blocks(struct ext4_sb_info *sbi,