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author | Chris Mason <chris.mason@oracle.com> | 2011-03-07 11:10:24 -0500 |
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committer | Chris Mason <chris.mason@oracle.com> | 2011-03-07 11:10:24 -0500 |
commit | 31339acd07b4ba687906702085127895a56eb920 (patch) | |
tree | c1f2d464acfc97e8c5faecf57e644578cccce94d /fs/btrfs | |
parent | b1bf862e9dad431175a1174379476299dbfdc017 (diff) | |
download | kernel_samsung_tuna-31339acd07b4ba687906702085127895a56eb920.zip kernel_samsung_tuna-31339acd07b4ba687906702085127895a56eb920.tar.gz kernel_samsung_tuna-31339acd07b4ba687906702085127895a56eb920.tar.bz2 |
Btrfs: deal with short returns from copy_from_user
When copy_from_user is only able to copy some of the bytes we requested,
we may end up creating a partially up to date page. To avoid garbage in
the page, we need to treat a partial copy as a zero length copy.
This makes the rest of the file_write code drop the page and
retry the whole copy instead of marking the partially up to
date page as dirty.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
cc: stable@kernel.org
Diffstat (limited to 'fs/btrfs')
-rw-r--r-- | fs/btrfs/file.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 13664b3..ab22ca4 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -69,6 +69,19 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages, /* Flush processor's dcache for this page */ flush_dcache_page(page); + + /* + * if we get a partial write, we can end up with + * partially up to date pages. These add + * a lot of complexity, so make sure they don't + * happen by forcing this copy to be retried. + * + * The rest of the btrfs_file_write code will fall + * back to page at a time copies after we return 0. + */ + if (!PageUptodate(page) && copied < count) + copied = 0; + iov_iter_advance(i, copied); write_bytes -= copied; total_copied += copied; |