On Thu 29-09-16 16:49:25, Ross Zwisler wrote: > DAX radix tree locking currently locks entries based on the unique > combination of the 'mapping' pointer and the pgoff_t 'index' for the entry. > This works for PTEs, but as we move to PMDs we will need to have all the > offsets within the range covered by the PMD to map to the same bit lock. > To accomplish this, for ranges covered by a PMD entry we will instead lock > based on the page offset of the beginning of the PMD entry. The 'mapping' > pointer is still used in the same way. > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > --- > fs/dax.c | 37 ++++++++++++++++++++++++------------- > include/linux/dax.h | 2 +- > mm/filemap.c | 2 +- > 3 files changed, 26 insertions(+), 15 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index baef586..406feea 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -64,10 +64,17 @@ static int __init init_dax_wait_table(void) > } > fs_initcall(init_dax_wait_table); > > +static pgoff_t dax_entry_start(pgoff_t index, void *entry) > +{ > + if (RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) > + index &= (PMD_MASK >> PAGE_SHIFT); Hum, but if we shift right, top bits of PMD_MASK will become zero - not something we want I guess... You rather want to mask with something like: ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1) > @@ -447,10 +457,11 @@ restart: > return entry; > } > > -void dax_wake_mapping_entry_waiter(struct address_space *mapping, > +void dax_wake_mapping_entry_waiter(void *entry, struct address_space *mapping, > pgoff_t index, bool wake_all) Nitpick: Ordering of arguments would look more logical to me like: dax_wake_mapping_entry_waiter(mapping, index, entry, wake_all) Other than that the patch looks good to me. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>