linux_dsm_epyc7002/fs/ext4
Kazuya Mio d02a9391f7 ext4: ensure f_bfree returned by ext4_statfs() is non-negative
I found the issue that the number of free blocks went negative.
# stat -f /mnt/mp1/
  File: "/mnt/mp1/"
    ID: e175ccb83a872efe Namelen: 255     Type: ext2/ext3
Block size: 4096       Fundamental block size: 4096
Blocks: Total: 258022     Free: -15        Available: -13122
Inodes: Total: 65536      Free: 63029

f_bfree in struct statfs will go negative when the filesystem has
few free blocks. Because the number of dirty blocks is bigger than
the number of free blocks in the following two cases.

CASE 1:
ext4_da_writepages
  mpage_da_map_and_submit
    ext4_map_blocks
      ext4_ext_map_blocks
        ext4_mb_new_blocks
          ext4_mb_diskspace_used
            percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);
        <--- interrupt statfs systemcall --->
        ext4_da_update_reserve_space
            percpu_counter_sub(&sbi->s_dirtyblocks_counter,
                            used + ei->i_allocated_meta_blocks);

CASE 2:
ext4_write_begin
  __block_write_begin
    ext4_map_blocks
      ext4_ext_map_blocks
        ext4_mb_new_blocks
          ext4_mb_diskspace_used
            percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);
            <--- interrupt statfs systemcall --->
            percpu_counter_sub(&sbi->s_dirtyblocks_counter, reserv_blks);

To avoid the issue, this patch ensures that f_bfree is non-negative.

Signed-off-by: Kazuya Mio <k-mio@sx.jp.nec.com>
2011-05-24 18:30:07 -04:00
..
acl.c userns: rename is_owner_or_cap to inode_owner_or_capable 2011-03-23 19:47:13 -07:00
acl.h fs: provide rcu-walk aware permission i_ops 2011-01-07 17:50:29 +11:00
balloc.c ext4: move ext4_add_groupblocks() to mballoc.c 2011-05-09 10:46:41 -04:00
bitmap.c ext4: Change unsigned long to unsigned int 2008-11-05 00:14:04 -05:00
block_validity.c ext4: rename {exit,init}_ext4_*() to ext4_{exit,init}_*() 2010-10-27 21:30:14 -04:00
dir.c ext4: Use ext4_error_file() to print the pathname to the corrupted inode 2011-01-10 12:10:55 -05:00
ext4_extents.h ext4: drop ec_type from the ext4_ext_cache structure 2011-01-10 12:13:26 -05:00
ext4_jbd2.c ext4: remove unneeded ext4_journal_get_undo_access 2011-05-09 10:58:45 -04:00
ext4_jbd2.h ext4: remove unneeded ext4_journal_get_undo_access 2011-05-09 10:58:45 -04:00
ext4.h ext4: count hits/misses of extent cache and expose in sysfs 2011-05-22 21:24:16 -04:00
extents.c ext4: fix ext4_ext_fiemap_cb() to handle blocks before request range correctly 2011-05-24 11:36:58 -04:00
file.c ext4: serialize unaligned asynchronous DIO 2011-02-12 08:17:34 -05:00
fsync.c ext4: fix waiting and sending of a barrier in ext4_sync_file() 2011-05-24 12:00:54 -04:00
hash.c ext4: Add support for non-native signed/unsigned htree hash algorithms 2008-10-28 13:21:44 -04:00
ialloc.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2011-03-25 09:57:41 -07:00
inode.c ext4: use truncate_setsize() unconditionally 2011-05-23 15:13:02 -04:00
ioctl.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2011-03-25 09:57:41 -07:00
Kconfig ext4: Don't ask about supporting ext2/3 in ext4 if ext4 is not configured 2009-12-21 10:54:09 -05:00
Makefile ext4: use bio layer instead of buffer layer in mpage_da_submit_io 2010-10-27 21:30:10 -04:00
mballoc.c ext4: protect bb_first_free in ext4_trim_all_free() with group lock 2011-05-24 18:28:07 -04:00
mballoc.h ext4: remove alloc_semp 2011-05-09 21:52:36 -04:00
migrate.c ext4: set extents flag when migrating file to use extents 2011-05-03 09:34:42 -04:00
move_extent.c ext4: clean up some wait_on_page_writeback calls 2011-05-18 13:53:20 -04:00
namei.c ext4: don't dereference null pointer when make_indexed_dir() fails 2011-05-15 00:19:41 -04:00
page-io.c ext4: don't set PageUptodate in ext4_end_bio() 2011-04-30 13:26:26 -04:00
resize.c ext4: unify the ext4_handle_release_buffer() api 2011-03-20 22:57:02 -04:00
super.c ext4: ensure f_bfree returned by ext4_statfs() is non-negative 2011-05-24 18:30:07 -04:00
symlink.c ext4: symlink must be handled via filesystem specific operation 2010-05-16 02:00:00 -04:00
xattr_security.c fs/vfs/security: pass last path component to LSM on inode creation 2011-02-01 11:12:29 -05:00
xattr_trusted.c ext4: constify xattr_handler 2010-05-21 18:31:19 -04:00
xattr_user.c ext4: constify xattr_handler 2010-05-21 18:31:19 -04:00
xattr.c ext4: unify the ext4_handle_release_buffer() api 2011-03-20 22:57:02 -04:00
xattr.h fs/vfs/security: pass last path component to LSM on inode creation 2011-02-01 11:12:29 -05:00