Instead of calling xfs_zero_eof with the ilock held only take it internally
for the minimall required critical section around xfs_bmapi_read. This
also requires changing the calling convention for xfs_zero_last_block
slightly. The actual zeroing operation is still serialized by the iolock,
which must be taken exclusively over the call to xfs_zero_eof.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_file.c | 161 ++++++++++++++++++++----------------------------------
fs/xfs/xfs_iops.c | 2
2 files changed, 62 insertions(+), 101 deletions(-)
Index: xfs/fs/xfs/xfs_file.c
===================================================================
--- xfs.orig/fs/xfs/xfs_file.c 2012-03-26 21:24:07.955268625 +0200
+++ xfs/fs/xfs/xfs_file.c 2012-03-26 21:24:14.588566021 +0200
@@ -396,114 +396,96 @@ xfs_file_splice_write(
}
/*
- * This routine is called to handle zeroing any space in the last
- * block of the file that is beyond the EOF. We do this since the
- * size is being increased without writing anything to that block
- * and we don't want anyone to read the garbage on the disk.
+ * This routine is called to handle zeroing any space in the last block of the
+ * file that is beyond the EOF. We do this since the size is being increased
+ * without writing anything to that block and we don't want to read the
+ * garbage on the disk.
*/
STATIC int /* error (positive) */
xfs_zero_last_block(
- xfs_inode_t *ip,
- xfs_fsize_t offset,
- xfs_fsize_t isize)
+ struct xfs_inode *ip,
+ xfs_fsize_t offset,
+ xfs_fsize_t isize)
{
- xfs_fileoff_t last_fsb;
- xfs_mount_t *mp = ip->i_mount;
- int nimaps;
- int zero_offset;
- int zero_len;
- int error = 0;
- xfs_bmbt_irec_t imap;
-
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
-
- zero_offset = XFS_B_FSB_OFFSET(mp, isize);
- if (zero_offset == 0) {
- /*
- * There are no extra bytes in the last block on disk to
- * zero, so return.
- */
- return 0;
- }
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t last_fsb = XFS_B_TO_FSBT(mp, isize);
+ int zero_offset = XFS_B_FSB_OFFSET(mp, isize);
+ int zero_len;
+ int nimaps = 1;
+ int error = 0;
+ struct xfs_bmbt_irec imap;
- last_fsb = XFS_B_TO_FSBT(mp, isize);
- nimaps = 1;
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_bmapi_read(ip, last_fsb, 1, &imap, &nimaps, 0);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
+
ASSERT(nimaps > 0);
+
/*
* If the block underlying isize is just a hole, then there
* is nothing to zero.
*/
- if (imap.br_startblock == HOLESTARTBLOCK) {
+ if (imap.br_startblock == HOLESTARTBLOCK)
return 0;
- }
- /*
- * Zero the part of the last block beyond the EOF, and write it
- * out sync. We need to drop the ilock while we do this so we
- * don't deadlock when the buffer cache calls back to us.
- */
- xfs_iunlock(ip, XFS_ILOCK_EXCL);
zero_len = mp->m_sb.sb_blocksize - zero_offset;
if (isize + zero_len > offset)
zero_len = offset - isize;
- error = xfs_iozero(ip, isize, zero_len);
-
- xfs_ilock(ip, XFS_ILOCK_EXCL);
- ASSERT(error >= 0);
- return error;
+ return xfs_iozero(ip, isize, zero_len);
}
/*
- * Zero any on disk space between the current EOF and the new,
- * larger EOF. This handles the normal case of zeroing the remainder
- * of the last block in the file and the unusual case of zeroing blocks
- * out beyond the size of the file. This second case only happens
- * with fixed size extents and when the system crashes before the inode
- * size was updated but after blocks were allocated. If fill is set,
- * then any holes in the range are filled and zeroed. If not, the holes
- * are left alone as holes.
+ * Zero any on disk space between the current EOF and the new, larger EOF.
+ *
+ * This handles the normal case of zeroing the remainder of the last block in
+ * the file and the unusual case of zeroing blocks out beyond the size of the
+ * file. This second case only happens with fixed size extents and when the
+ * system crashes before the inode size was updated but after blocks were
+ * allocated.
+ *
+ * Expects the iolock to be held exclusive, and will take the ilock internally.
*/
-
int /* error (positive) */
xfs_zero_eof(
- xfs_inode_t *ip,
- xfs_off_t offset, /* starting I/O offset */
- xfs_fsize_t isize) /* current inode size */
+ struct xfs_inode *ip,
+ xfs_off_t offset, /* starting I/O offset */
+ xfs_fsize_t isize) /* current inode size */
{
- xfs_mount_t *mp = ip->i_mount;
- xfs_fileoff_t start_zero_fsb;
- xfs_fileoff_t end_zero_fsb;
- xfs_fileoff_t zero_count_fsb;
- xfs_fileoff_t last_fsb;
- xfs_fileoff_t zero_off;
- xfs_fsize_t zero_len;
- int nimaps;
- int error = 0;
- xfs_bmbt_irec_t imap;
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t start_zero_fsb;
+ xfs_fileoff_t end_zero_fsb;
+ xfs_fileoff_t zero_count_fsb;
+ xfs_fileoff_t last_fsb;
+ xfs_fileoff_t zero_off;
+ xfs_fsize_t zero_len;
+ int nimaps;
+ int error = 0;
+ struct xfs_bmbt_irec imap;
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
+ ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
ASSERT(offset > isize);
/*
* First handle zeroing the block on which isize resides.
+ *
* We only zero a part of that block so it is handled specially.
*/
- error = xfs_zero_last_block(ip, offset, isize);
- if (error) {
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
- return error;
+ if (XFS_B_FSB_OFFSET(mp, isize) != 0) {
+ error = xfs_zero_last_block(ip, offset, isize);
+ if (error)
+ return error;
}
/*
- * Calculate the range between the new size and the old
- * where blocks needing to be zeroed may exist. To get the
- * block where the last byte in the file currently resides,
- * we need to subtract one from the size and truncate back
- * to a block boundary. We subtract 1 in case the size is
- * exactly on a block boundary.
+ * Calculate the range between the new size and the old where blocks
+ * needing to be zeroed may exist.
+ *
+ * To get the block where the last byte in the file currently resides,
+ * we need to subtract one from the size and truncate back to a block
+ * boundary. We subtract 1 in case the size is exactly on a block
+ * boundary.
*/
last_fsb = isize ? XFS_B_TO_FSBT(mp, isize - 1) : (xfs_fileoff_t)-1;
start_zero_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)isize);
@@ -521,23 +503,18 @@ xfs_zero_eof(
while (start_zero_fsb <= end_zero_fsb) {
nimaps = 1;
zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_bmapi_read(ip, start_zero_fsb, zero_count_fsb,
&imap, &nimaps, 0);
- if (error) {
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ if (error)
return error;
- }
+
ASSERT(nimaps > 0);
if (imap.br_state == XFS_EXT_UNWRITTEN ||
imap.br_startblock == HOLESTARTBLOCK) {
- /*
- * This loop handles initializing pages that were
- * partially initialized by the code below this
- * loop. It basically zeroes the part of the page
- * that sits on a hole and sets the page as P_HOLE
- * and calls remapf if it is a mapped file.
- */
start_zero_fsb = imap.br_startoff + imap.br_blockcount;
ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
continue;
@@ -545,11 +522,7 @@ xfs_zero_eof(
/*
* There are blocks we need to zero.
- * Drop the inode lock while we're doing the I/O.
- * We'll still have the iolock to protect us.
*/
- xfs_iunlock(ip, XFS_ILOCK_EXCL);
-
zero_off = XFS_FSB_TO_B(mp, start_zero_fsb);
zero_len = XFS_FSB_TO_B(mp, imap.br_blockcount);
@@ -557,22 +530,14 @@ xfs_zero_eof(
zero_len = offset - zero_off;
error = xfs_iozero(ip, zero_off, zero_len);
- if (error) {
- goto out_lock;
- }
+ if (error)
+ return error;
start_zero_fsb = imap.br_startoff + imap.br_blockcount;
ASSERT(start_zero_fsb <= (end_zero_fsb + 1));
-
- xfs_ilock(ip, XFS_ILOCK_EXCL);
}
return 0;
-
-out_lock:
- xfs_ilock(ip, XFS_ILOCK_EXCL);
- ASSERT(error >= 0);
- return error;
}
/*
@@ -612,9 +577,7 @@ restart:
xfs_rw_ilock(ip, *iolock);
goto restart;
}
- xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
error = -xfs_zero_eof(ip, *pos, i_size_read(inode));
- xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
}
Index: xfs/fs/xfs/xfs_iops.c
===================================================================
--- xfs.orig/fs/xfs/xfs_iops.c 2012-03-26 21:24:13.791903671 +0200
+++ xfs/fs/xfs/xfs_iops.c 2012-03-26 21:24:14.588566021 +0200
@@ -764,9 +764,7 @@ xfs_setattr_size(
* before the inode is joined to the transaction to modify
* i_size.
*/
- xfs_ilock(ip, XFS_ILOCK_EXCL);
error = xfs_zero_eof(ip, newsize, oldsize);
- xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
goto out_unlock;
}
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