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author | Lachlan McIlroy <lachlan@sgi.com> | 2008-09-17 16:50:14 +1000 |
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committer | Lachlan McIlroy <lachlan@redback.melbourne.sgi.com> | 2008-09-17 16:50:14 +1000 |
commit | 364f358a734ddcd827c662ccbfa58ee3ac510762 (patch) | |
tree | 2af362aa418b145e0626066ed2c8b3b0918630eb /fs/xfs | |
parent | 6efdf281777eb07fac28ac2b2d7df1e619ee6da1 (diff) | |
download | op-kernel-dev-364f358a734ddcd827c662ccbfa58ee3ac510762.zip op-kernel-dev-364f358a734ddcd827c662ccbfa58ee3ac510762.tar.gz |
[XFS] Prevent direct I/O from mapping extents beyond eof
With the help from some tracing I found that we try to map extents beyond
eof when doing a direct I/O read. It appears that the way to inform the
generic direct I/O path (ie do_direct_IO()) that we have breached eof is
to return an unmapped buffer from xfs_get_blocks_direct(). This will cause
do_direct_IO() to jump to the hole handling code where is will check for
eof and then abort.
This problem was found because a direct I/O read was trying to map beyond
eof and was encountering delayed allocations. The delayed allocations
beyond eof are speculative allocations and they didn't get converted when
the direct I/O flushed the file because there was only enough space in the
current AG to convert and write out the dirty pages within eof. Note that
xfs_iomap_write_allocate() wont necessarily convert all the delayed
allocation passed to it - it will return after allocating the first extent
- so if the delayed allocation extends beyond eof then it will stay that
way.
SGI-PV: 983683
SGI-Modid: xfs-linux-melb:xfs-kern:31929a
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Diffstat (limited to 'fs/xfs')
-rw-r--r-- | fs/xfs/linux-2.6/xfs_aops.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index f42f80a..a44d68e 100644 --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -1338,6 +1338,10 @@ __xfs_get_blocks( offset = (xfs_off_t)iblock << inode->i_blkbits; ASSERT(bh_result->b_size >= (1 << inode->i_blkbits)); size = bh_result->b_size; + + if (!create && direct && offset >= i_size_read(inode)) + return 0; + error = xfs_iomap(XFS_I(inode), offset, size, create ? flags : BMAPI_READ, &iomap, &niomap); if (error) |