Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 14:11:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

xfs: reserve blocks for truncating large realtime inode

Browse Source 
When unaligned truncate down a big realtime file, xfs_truncate_page()
only zeros out the tail EOF block, __xfs_bunmapi() should split the tail
written extent and convert the later one that beyond EOF block to
unwritten, but it couldn't work as expected now since the reserved block
is zero in xfs_setattr_size(), this could expose stale data just after
commit '943bc0882ceb ("iomap: don't increase i_size if it's not a write
operation")'.

If we truncate file that contains a large enough written extent:

     |<    rxext    >|<    rtext    >|
  ...WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW
        ^ (new EOF)      ^ old EOF

Since we only zeros out the tail of the EOF block, and
xfs_itruncate_extents()->..->__xfs_bunmapi() unmap the whole ailgned
extents, it becomes this state:

     |<    rxext    >|
  ...WWWzWWWWWWWWWWWWW
        ^ new EOF

Then if we do an extending write like this, the blocks in the previous
tail extent becomes stale:

     |<    rxext    >|
  ...WWWzSSSSSSSSSSSSS..........WWWWWWWWWWWWWWWWW
        ^ old EOF               ^ append start  ^ new EOF

Fix this by reserving XFS_DIOSTRAT_SPACE_RES blocks for big realtime
inode.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20240618142112.1315279-2-yi.zhang@huaweicloud.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Zhang Yi 2024-06-18 22:21:11 +08:00 committed by Christian Brauner
parent a7ca193bc9
commit d048945150
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 14 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/xfs/xfs_iops.c
View File

@ -17,6 +17,8 @@
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
#include "xfs_bmap_btree.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_symlink.h"
@ -811,6 +813,7 @@ xfs_setattr_size(
struct xfs_trans *tp;
int error;
uint lock_flags = 0;
uint resblks = 0;
bool did_zeroing = false;
xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
@ -917,7 +920,17 @@ xfs_setattr_size(
return error;
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
/*
* For realtime inode with more than one block rtextsize, we need the
* block reservation for bmap btree block allocations/splits that can
* happen since it could split the tail written extent and convert the
* right beyond EOF one to unwritten.
*/
if (xfs_inode_has_bigrtalloc(ip))
resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks,
0, 0, &tp);
if (error)
return error;