diff options
| author | Jan Kara <jack@suse.com> | 2015-12-07 15:10:26 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2015-12-07 15:10:26 -0500 |
| commit | c86d8db33a922da808a5560aa15ed663a9569b37 (patch) | |
| tree | 64ee357906cb5d2a0408a9613532460e49b7b6c9 /fs/ext4 | |
| parent | 53085fac02d12fcd29a9cb074ec480ff0f77ae5c (diff) | |
ext4: implement allocation of pre-zeroed blocks
DAX page fault path needs to get blocks that are pre-zeroed to avoid
races when two concurrent page faults happen in the same block of a
file. Implement support for this in ext4_map_blocks().
Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/ext4.h | 4 | ||||
| -rw-r--r-- | fs/ext4/extents.c | 8 | ||||
| -rw-r--r-- | fs/ext4/inode.c | 25 |
3 files changed, 34 insertions, 3 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index ffc6ab000c78..ae900b530d37 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -557,6 +557,10 @@ enum { #define EXT4_GET_BLOCKS_KEEP_SIZE 0x0080 /* Convert written extents to unwritten */ #define EXT4_GET_BLOCKS_CONVERT_UNWRITTEN 0x0100 + /* Write zeros to newly created written extents */ +#define EXT4_GET_BLOCKS_ZERO 0x0200 +#define EXT4_GET_BLOCKS_CREATE_ZERO (EXT4_GET_BLOCKS_CREATE |\ + EXT4_GET_BLOCKS_ZERO) /* * The bit position of these flags must not overlap with any of the diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 867e98b6bc6c..b52fea3b7219 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4044,6 +4044,14 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode, } /* IO end_io complete, convert the filled extent to written */ if (flags & EXT4_GET_BLOCKS_CONVERT) { + if (flags & EXT4_GET_BLOCKS_ZERO) { + if (allocated > map->m_len) + allocated = map->m_len; + err = ext4_issue_zeroout(inode, map->m_lblk, newblock, + allocated); + if (err < 0) + goto out2; + } ret = ext4_convert_unwritten_extents_endio(handle, inode, map, ppath); if (ret >= 0) { diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 0c9a5ee3e106..4241d0cff062 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -637,13 +637,29 @@ found: } /* + * We have to zeroout blocks before inserting them into extent + * status tree. Otherwise someone could look them up there and + * use them before they are really zeroed. + */ + if (flags & EXT4_GET_BLOCKS_ZERO && + map->m_flags & EXT4_MAP_MAPPED && + map->m_flags & EXT4_MAP_NEW) { + ret = ext4_issue_zeroout(inode, map->m_lblk, + map->m_pblk, map->m_len); + if (ret) { + retval = ret; + goto out_sem; + } + } + + /* * If the extent has been zeroed out, we don't need to update * extent status tree. */ if ((flags & EXT4_GET_BLOCKS_PRE_IO) && ext4_es_lookup_extent(inode, map->m_lblk, &es)) { if (ext4_es_is_written(&es)) - goto has_zeroout; + goto out_sem; } status = map->m_flags & EXT4_MAP_UNWRITTEN ? EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN; @@ -654,11 +670,13 @@ found: status |= EXTENT_STATUS_DELAYED; ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len, map->m_pblk, status); - if (ret < 0) + if (ret < 0) { retval = ret; + goto out_sem; + } } -has_zeroout: +out_sem: up_write((&EXT4_I(inode)->i_data_sem)); if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) { ret = check_block_validity(inode, map); @@ -3083,6 +3101,7 @@ int ext4_get_block_dax(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { int flags = EXT4_GET_BLOCKS_PRE_IO | EXT4_GET_BLOCKS_UNWRIT_EXT; + if (create) flags |= EXT4_GET_BLOCKS_CREATE; ext4_debug("ext4_get_block_dax: inode %lu, create flag %d\n", |