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xfs: truncate should remove all blocks, not just to the end of the page cache 

xfs_itruncate_extents_flags() is supposed to unmap every block in a file
from EOF onwards.  Oddly, it uses s_maxbytes as the upper limit to the
bunmapi range, even though s_maxbytes reflects the highest offset the
pagecache can support, not the highest offset that XFS supports.

The result of this confusion is that if you create a 20T file on a
64-bit machine, mount the filesystem on a 32-bit machine, and remove the
file, we leak everything above 16T.  Fix this by capping the bunmapi
request at the maximum possible block offset, not s_maxbytes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2020-01-02 13:20:13 -08:00
parent a508486552
commit 4bbb04abb4
1 changed files with 12 additions and 12 deletions
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24
fs/xfs/xfs_inode.c
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@ -1518,7 +1518,6 @@ xfs_itruncate_extents_flags(
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp = *tpp;
xfs_fileoff_t first_unmap_block;
xfs_fileoff_t last_block;
xfs_filblks_t unmap_len;
int error = 0;
int done = 0;
@ -1541,21 +1540,22 @@ xfs_itruncate_extents_flags(
* the end of the file (in a crash where the space is allocated
* but the inode size is not yet updated), simply remove any
* blocks which show up between the new EOF and the maximum
* possible file size. If the first block to be removed is
* beyond the maximum file size (ie it is the same as last_block),
* then there is nothing to do.
* possible file size.
*
* We have to free all the blocks to the bmbt maximum offset, even if
* the page cache can't scale that far.
*/
first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
last_block = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
if (first_unmap_block == last_block)
if (first_unmap_block >= XFS_MAX_FILEOFF) {
WARN_ON_ONCE(first_unmap_block > XFS_MAX_FILEOFF);
return 0;
}
ASSERT(first_unmap_block < last_block);
unmap_len = last_block - first_unmap_block + 1;
while (!done) {
unmap_len = XFS_MAX_FILEOFF - first_unmap_block + 1;
while (unmap_len > 0) {
ASSERT(tp->t_firstblock == NULLFSBLOCK);
error = xfs_bunmapi(tp, ip, first_unmap_block, unmap_len, flags,
XFS_ITRUNC_MAX_EXTENTS, &done);
error = __xfs_bunmapi(tp, ip, first_unmap_block, &unmap_len,
flags, XFS_ITRUNC_MAX_EXTENTS);
if (error)
goto out;
@ -1575,7 +1575,7 @@ xfs_itruncate_extents_flags(
if (whichfork == XFS_DATA_FORK) {
/* Remove all pending CoW reservations. */
error = xfs_reflink_cancel_cow_blocks(ip, &tp,
first_unmap_block, last_block, true);
first_unmap_block, XFS_MAX_FILEOFF, true);
if (error)
goto out;