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| author | Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> | 2018-10-08 20:58:23 -0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-01-22 08:26:44 -0700 |
| commit | 8b9433eb4de3c26a9226c981c283f9f4896ae030 (patch) | |
| tree | d38a0f272d3ca37799f97cd4b63eb4a088747808 /fs/direct-io.c | |
| parent | 38197ca176fc259fa4c871d07bcf8389d044a895 (diff) | |
| download | lwn-8b9433eb4de3c26a9226c981c283f9f4896ae030.tar.gz lwn-8b9433eb4de3c26a9226c981c283f9f4896ae030.zip | |
direct-io: allow direct writes to empty inodes
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>
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index dbc1a1f080ce..ec2fb6fe6d37 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; } |