Maxim Patlasov <mpatla...@virtuozzo.com> writes:
> While handling fallocate(), ext4 firstly calls ext4_update_inode_size(), > then ext4_mark_inode_dirty(). Both update only in-core state. After > fallocate(), ploop updates BAT bypassing vfs layer (submit bio to > underlying block device). Hence, it's possible that BAT is already > updated, but i_size in now written to the disk yet. If a crash happens > in the middle, BAT points beyond end-of-file, i.e. ploop image is > corrupted. > > The patch fixes the problem by ordinary fsync(). This is OK because > we fallocate relatively seldom (PLOOP_MAX_PREALLOC=128MB) and also > because no dirty pages to sync (all I/O is direct). > > https://jira.sw.ru/browse/PSBM-45326 ACK > > Signed-off-by: Maxim Patlasov <mpatla...@virtuozzo.com> > --- > drivers/block/ploop/io_direct.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c > index 0c7e0c4..8032999 100644 > --- a/drivers/block/ploop/io_direct.c > +++ b/drivers/block/ploop/io_direct.c > @@ -376,6 +376,7 @@ cached_submit(struct ploop_io *io, iblock_t iblk, struct > ploop_request * preq, > loff_t new_size; > loff_t used_pos; > bool may_fallocate = io->files.file->f_op->fallocate && > + io->files.file->f_op->fsync && > io->files.flags & EXT4_EXTENTS_FL; > > trace_cached_submit(preq); > @@ -404,6 +405,11 @@ try_again: > } > } > > + /* flush new i_size to disk */ > + err = io->files.file->f_op->FOP_FSYNC(io->files.file, > 0); > + if (err) > + goto end_write; > + > io->prealloced_size = prealloc; > } >
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