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authorErnesto A. Fernández <ernesto.mnd.fernandez@gmail.com>2018-10-08 20:58:23 -0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-03-05 17:58:50 +0100
commitc5a1dc256cc2ac6c08f637994e513a8cb65be3d6 (patch)
treebd4d4943efc33f5f88551cd646974505c1d54d24
parentbcb8e0a236989f8efccb6ca2218ad4871a26c00b (diff)
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direct-io: allow direct writes to empty inodes
[ Upstream commit 8b9433eb4de3c26a9226c981c283f9f4896ae030 ] On a DIO_SKIP_HOLES filesystem, the ->get_block() method is currently not allowed to create blocks for an empty inode. This confusion comes from trying to bit shift a negative number, so check the size of the inode first. The problem is most visible for hfsplus, because the fallback to buffered I/O doesn't happen and the write fails with EIO. This is in part the fault of the module, because it gives a wrong return value on ->get_block(); that will be fixed in a separate patch. Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--fs/direct-io.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 199146036093..1abb7634b2d5 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -679,6 +679,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
unsigned long fs_count; /* Number of filesystem-sized blocks */
int create;
unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;
+ loff_t i_size;
/*
* If there was a memory error and we've overwritten all the
@@ -708,8 +709,8 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
*/
create = dio->op == REQ_OP_WRITE;
if (dio->flags & DIO_SKIP_HOLES) {
- if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
- i_blkbits))
+ i_size = i_size_read(dio->inode);
+ if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits)
create = 0;
}