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authorChristoph Hellwig <hch@infradead.org>2009-10-19 04:03:46 +0000
committerAlex Elder <aelder@sgi.com>2009-12-11 15:11:19 -0600
commitc56c9631cbe88f08854a56ff9776c1f310916830 (patch)
tree9069de0b572857072bc99334b8d5e1bce14ef13f
parent848ce8f731aed0a2d4ab5884a4f6664af73d2dd0 (diff)
downloadop-kernel-dev-c56c9631cbe88f08854a56ff9776c1f310916830.zip
op-kernel-dev-c56c9631cbe88f08854a56ff9776c1f310916830.tar.gz
xfs: fix mmap_sem/iolock inversion in xfs_free_eofblocks
When xfs_free_eofblocks is called from ->release the VM might already hold the mmap_sem, but in the write path we take the iolock before taking the mmap_sem in the generic write code. Switch xfs_free_eofblocks to only trylock the iolock if called from ->release and skip trimming the prellocated blocks in that case. We'll still free them later on the final iput. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com> Signed-off-by: Alex Elder <aelder@sgi.com>
-rw-r--r--fs/xfs/xfs_rw.h7
-rw-r--r--fs/xfs/xfs_vnodeops.c34
2 files changed, 26 insertions, 15 deletions
diff --git a/fs/xfs/xfs_rw.h b/fs/xfs/xfs_rw.h
index f5e4874..726014d 100644
--- a/fs/xfs/xfs_rw.h
+++ b/fs/xfs/xfs_rw.h
@@ -37,13 +37,6 @@ xfs_fsb_to_db(struct xfs_inode *ip, xfs_fsblock_t fsb)
}
/*
- * Flags for xfs_free_eofblocks
- */
-#define XFS_FREE_EOF_LOCK (1<<0)
-#define XFS_FREE_EOF_NOLOCK (1<<1)
-
-
-/*
* helper function to extract extent size hint from inode
*/
STATIC_INLINE xfs_extlen_t
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 3fac146..d984014 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -709,6 +709,11 @@ xfs_fsync(
}
/*
+ * Flags for xfs_free_eofblocks
+ */
+#define XFS_FREE_EOF_TRYLOCK (1<<0)
+
+/*
* This is called by xfs_inactive to free any blocks beyond eof
* when the link count isn't zero and by xfs_dm_punch_hole() when
* punching a hole to EOF.
@@ -726,7 +731,6 @@ xfs_free_eofblocks(
xfs_filblks_t map_len;
int nimaps;
xfs_bmbt_irec_t imap;
- int use_iolock = (flags & XFS_FREE_EOF_LOCK);
/*
* Figure out if there are any blocks beyond the end
@@ -768,14 +772,19 @@ xfs_free_eofblocks(
* cache and we can't
* do that within a transaction.
*/
- if (use_iolock)
+ if (flags & XFS_FREE_EOF_TRYLOCK) {
+ if (!xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
+ xfs_trans_cancel(tp, 0);
+ return 0;
+ }
+ } else {
xfs_ilock(ip, XFS_IOLOCK_EXCL);
+ }
error = xfs_itruncate_start(ip, XFS_ITRUNC_DEFINITE,
ip->i_size);
if (error) {
xfs_trans_cancel(tp, 0);
- if (use_iolock)
- xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+ xfs_iunlock(ip, XFS_IOLOCK_EXCL);
return error;
}
@@ -812,8 +821,7 @@ xfs_free_eofblocks(
error = xfs_trans_commit(tp,
XFS_TRANS_RELEASE_LOG_RES);
}
- xfs_iunlock(ip, (use_iolock ? (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)
- : XFS_ILOCK_EXCL));
+ xfs_iunlock(ip, XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL);
}
return error;
}
@@ -1113,7 +1121,17 @@ xfs_release(
(ip->i_df.if_flags & XFS_IFEXTENTS)) &&
(!(ip->i_d.di_flags &
(XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)))) {
- error = xfs_free_eofblocks(mp, ip, XFS_FREE_EOF_LOCK);
+
+ /*
+ * If we can't get the iolock just skip truncating
+ * the blocks past EOF because we could deadlock
+ * with the mmap_sem otherwise. We'll get another
+ * chance to drop them once the last reference to
+ * the inode is dropped, so we'll never leak blocks
+ * permanently.
+ */
+ error = xfs_free_eofblocks(mp, ip,
+ XFS_FREE_EOF_TRYLOCK);
if (error)
return error;
}
@@ -1184,7 +1202,7 @@ xfs_inactive(
(!(ip->i_d.di_flags &
(XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)) ||
(ip->i_delayed_blks != 0)))) {
- error = xfs_free_eofblocks(mp, ip, XFS_FREE_EOF_LOCK);
+ error = xfs_free_eofblocks(mp, ip, 0);
if (error)
return VN_INACTIVE_CACHE;
}
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