From: Ernesto A. Fernández ernesto.mnd.fernandez@gmail.com
[ 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 --- fs/direct-io.c | 5 +++-- 1 file 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; }