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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>
This commit is contained in:
Eric Sandeen 2008-10-28 00:08:17 -04:00 committed by Theodore Ts'o
parent 8c3bf8a01c
commit a996031c87
1 changed files with 14 additions and 12 deletions
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26
fs/ext4/balloc.c
View File

@ -599,18 +599,13 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
*/
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 @@ int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
}
}
/* 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,