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xfs: kill xfs_itruncate_start

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xfs_itruncate_start is a rather length wrapper that evaluates to a call
to xfs_ioend_wait and xfs_tosspages, and only has two callers.

Instead of using the complicated checks left over from IRIX where we
can to truncate the pagecache just call xfs_tosspages
(aka truncate_inode_pages) directly as we want to get rid of all data
after i_size, and truncate_inode_pages handles incorrect alignments
and too large offsets just fine.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Christoph Hellwig
2011-07-08 14:34:30 +02:00
parent 681b120018
commit 857b9778d8
4 changed files with 4 additions and 231 deletions
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163
fs/xfs/xfs_inode.c
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@@ -1217,165 +1217,8 @@ xfs_isize_check(
#endif /* DEBUG */
/*
* Calculate the last possible buffered byte in a file. This must
* include data that was buffered beyond the EOF by the write code.
* This also needs to deal with overflowing the xfs_fsize_t type
* which can happen for sizes near the limit.
*
* We also need to take into account any blocks beyond the EOF. It
* may be the case that they were buffered by a write which failed.
* In that case the pages will still be in memory, but the inode size
* will never have been updated.
*/
STATIC xfs_fsize_t
xfs_file_last_byte(
xfs_inode_t *ip)
{
xfs_mount_t *mp;
xfs_fsize_t last_byte;
xfs_fileoff_t last_block;
xfs_fileoff_t size_last_block;
int error;
ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED));
mp = ip->i_mount;
/*
* Only check for blocks beyond the EOF if the extents have
* been read in. This eliminates the need for the inode lock,
* and it also saves us from looking when it really isn't
* necessary.
*/
if (ip->i_df.if_flags & XFS_IFEXTENTS) {
xfs_ilock(ip, XFS_ILOCK_SHARED);
error = xfs_bmap_last_offset(NULL, ip, &last_block,
XFS_DATA_FORK);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error) {
last_block = 0;
}
} else {
last_block = 0;
}
size_last_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)ip->i_size);
last_block = XFS_FILEOFF_MAX(last_block, size_last_block);
last_byte = XFS_FSB_TO_B(mp, last_block);
if (last_byte < 0) {
return XFS_MAXIOFFSET(mp);
}
last_byte += (1 << mp->m_writeio_log);
if (last_byte < 0) {
return XFS_MAXIOFFSET(mp);
}
return last_byte;
}
/*
* Start the truncation of the file to new_size. The new size
* must be smaller than the current size. This routine will
* clear the buffer and page caches of file data in the removed
* range, and xfs_itruncate_finish() will remove the underlying
* disk blocks.
*
* The inode must have its I/O lock locked EXCLUSIVELY, and it
* must NOT have the inode lock held at all. This is because we're
* calling into the buffer/page cache code and we can't hold the
* inode lock when we do so.
*
* We need to wait for any direct I/Os in flight to complete before we
* proceed with the truncate. This is needed to prevent the extents
* being read or written by the direct I/Os from being removed while the
* I/O is in flight as there is no other method of synchronising
* direct I/O with the truncate operation. Also, because we hold
* the IOLOCK in exclusive mode, we prevent new direct I/Os from being
* started until the truncate completes and drops the lock. Essentially,
* the xfs_ioend_wait() call forms an I/O barrier that provides strict
* ordering between direct I/Os and the truncate operation.
*
* The flags parameter can have either the value XFS_ITRUNC_DEFINITE
* or XFS_ITRUNC_MAYBE. The XFS_ITRUNC_MAYBE value should be used
* in the case that the caller is locking things out of order and
* may not be able to call xfs_itruncate_finish() with the inode lock
* held without dropping the I/O lock. If the caller must drop the
* I/O lock before calling xfs_itruncate_finish(), then xfs_itruncate_start()
* must be called again with all the same restrictions as the initial
* call.
*/
int
xfs_itruncate_start(
xfs_inode_t *ip,
uint flags,
xfs_fsize_t new_size)
{
xfs_fsize_t last_byte;
xfs_off_t toss_start;
xfs_mount_t *mp;
int error = 0;
ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
ASSERT((new_size == 0) || (new_size <= ip->i_size));
ASSERT((flags == XFS_ITRUNC_DEFINITE) ||
(flags == XFS_ITRUNC_MAYBE));
mp = ip->i_mount;
/* wait for the completion of any pending DIOs */
if (new_size == 0 || new_size < ip->i_size)
xfs_ioend_wait(ip);
/*
* Call toss_pages or flushinval_pages to get rid of pages
* overlapping the region being removed. We have to use
* the less efficient flushinval_pages in the case that the
* caller may not be able to finish the truncate without
* dropping the inode's I/O lock. Make sure
* to catch any pages brought in by buffers overlapping
* the EOF by searching out beyond the isize by our
* block size. We round new_size up to a block boundary
* so that we don't toss things on the same block as
* new_size but before it.
*
* Before calling toss_page or flushinval_pages, make sure to
* call remapf() over the same region if the file is mapped.
* This frees up mapped file references to the pages in the
* given range and for the flushinval_pages case it ensures
* that we get the latest mapped changes flushed out.
*/
toss_start = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
toss_start = XFS_FSB_TO_B(mp, toss_start);
if (toss_start < 0) {
/*
* The place to start tossing is beyond our maximum
* file size, so there is no way that the data extended
* out there.
*/
return 0;
}
last_byte = xfs_file_last_byte(ip);
trace_xfs_itruncate_start(ip, new_size, flags, toss_start, last_byte);
if (last_byte > toss_start) {
if (flags & XFS_ITRUNC_DEFINITE) {
xfs_tosspages(ip, toss_start,
-1, FI_REMAPF_LOCKED);
} else {
error = xfs_flushinval_pages(ip, toss_start,
-1, FI_REMAPF_LOCKED);
}
}
#ifdef DEBUG
if (new_size == 0) {
ASSERT(VN_CACHED(VFS_I(ip)) == 0);
}
#endif
return error;
}
/*
* Shrink the file to the given new_size. The new size must be smaller than
* the current size. This will free up the underlying blocks in the removed
* range after a call to xfs_itruncate_start() or xfs_atruncate_start().
* Free up the underlying blocks past new_size. The new size must be
* smaller than the current size.
*
* The transaction passed to this routine must have made a permanent log
* reservation of at least XFS_ITRUNCATE_LOG_RES. This routine may commit the
@@ -1387,7 +1230,7 @@ xfs_itruncate_start(
* will be "held" within the returned transaction. This routine does NOT
* require any disk space to be reserved for it within the transaction.
*
* The fork parameter must be either xfs_attr_fork or xfs_data_fork, and it
* The fork parameter must be either XFS_ATTR_FORK or XFS_DATA_FORK, and it
* indicates the fork which is to be truncated. For the attribute fork we only
* support truncation to size 0.
*