Message ID | 20131001012903.28415.39499.stgit@birch.djwong.org |
---|---|
State | Superseded, archived |
Headers | show |
On Mon, 30 Sep 2013, Darrick J. Wong wrote: > Date: Mon, 30 Sep 2013 18:29:03 -0700 > From: Darrick J. Wong <darrick.wong@oracle.com> > To: tytso@mit.edu, darrick.wong@oracle.com > Cc: linux-ext4@vger.kernel.org > Subject: [PATCH 22/31] libext2fs: During punch, > only free a cluster if we're sure that all blocks in the cluster are being > punched > > When bigalloc is enabled, using ext2fs_block_alloc_stats2() to free any block > in a cluster has the effect of freeing the entire cluster. This is problematic > if a caller instructs us to punch, say, blocks 12-15 of a 16-block cluster, > because blocks 0-11 now point to a "free" cluster. > > The naive way to solve this problem is to see if any of the other blocks in > this logical cluster map to a physical cluster. If so, then we know that the > cluster is still in use and it mustn't be freed. Otherwise, we are punching > the last mapped block in this cluster, so we can free the cluster. > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > lib/ext2fs/bmap.c | 28 ++++++++++++++++++++++++++++ > lib/ext2fs/ext2fs.h | 3 +++ > lib/ext2fs/punch.c | 30 +++++++++++++++++++++++++----- > 3 files changed, 56 insertions(+), 5 deletions(-) > > > diff --git a/lib/ext2fs/bmap.c b/lib/ext2fs/bmap.c > index 5074587..a6e35a9 100644 > --- a/lib/ext2fs/bmap.c > +++ b/lib/ext2fs/bmap.c > @@ -173,6 +173,34 @@ static errcode_t implied_cluster_alloc(ext2_filsys fs, ext2_ino_t ino, > return 0; > } > > +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, > + struct ext2_inode *inode, blk64_t lblk, > + blk64_t *pblk) > +{ > + ext2_extent_handle_t handle; > + errcode_t retval; > + > + /* Need bigalloc and extents to be enabled */ > + *pblk = 0; > + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, > + EXT4_FEATURE_RO_COMPAT_BIGALLOC) || > + !(inode->i_flags & EXT4_EXTENTS_FL)) > + return 0; > + > + retval = ext2fs_extent_open2(fs, ino, inode, &handle); > + if (retval) > + goto out; > + > + retval = implied_cluster_alloc(fs, ino, inode, handle, lblk, pblk); > + if (retval) > + goto out2; > + > +out2: > + ext2fs_extent_free(handle); > +out: > + return retval; > +} > + > static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino, > struct ext2_inode *inode, > ext2_extent_handle_t handle, > diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h > index 9fef6d3..88da8db 100644 > --- a/lib/ext2fs/ext2fs.h > +++ b/lib/ext2fs/ext2fs.h > @@ -925,6 +925,9 @@ extern errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, > struct ext2_inode *inode, > char *block_buf, int bmap_flags, blk64_t block, > int *ret_flags, blk64_t *phys_blk); > +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, > + struct ext2_inode *inode, blk64_t lblk, > + blk64_t *pblk); > > #if 0 > /* bmove.c */ > diff --git a/lib/ext2fs/punch.c b/lib/ext2fs/punch.c > index 4471f46..e0193b0 100644 > --- a/lib/ext2fs/punch.c > +++ b/lib/ext2fs/punch.c > @@ -183,8 +183,8 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > ext2_extent_handle_t handle = 0; > struct ext2fs_extent extent; > errcode_t retval; > - blk64_t free_start, next; > - __u32 free_count, newlen; > + blk64_t free_start, next, lfree_start, pblk; > + __u32 free_count, newlen, cluster_freed; > int freed = 0; > int op; > > @@ -210,6 +210,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > /* Start of deleted region before extent; > adjust beginning of extent */ > free_start = extent.e_pblk; > + lfree_start = extent.e_lblk; > if (next > end) > free_count = end - extent.e_lblk + 1; > else > @@ -225,6 +226,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > dbg_printf("Case #%d\n", 2); > newlen = start - extent.e_lblk; > free_start = extent.e_pblk + newlen; > + lfree_start = extent.e_lblk + newlen; > free_count = extent.e_len - newlen; > extent.e_len = newlen; > } else { > @@ -240,6 +242,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > > extent.e_len = start - extent.e_lblk; > free_start = extent.e_pblk + extent.e_len; > + lfree_start = extent.e_lblk + extent.e_len; > free_count = end - start + 1; > > dbg_print_extent("inserting", &newex); > @@ -280,9 +283,26 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > goto errout; > dbg_printf("Free start %llu, free count = %u\n", > free_start, free_count); > - while (free_count-- > 0) { > - ext2fs_block_alloc_stats2(fs, free_start++, -1); > - freed++; > + while (free_count > 0) { > + retval = ext2fs_map_cluster_block(fs, ino, inode, > + lfree_start, &pblk); > + if (retval) > + goto errout; > + if (!pblk) { > + ext2fs_block_alloc_stats2(fs, free_start, -1); > + freed++; > + cluster_freed = EXT2FS_CLUSTER_RATIO(fs) - > + (free_start & EXT2FS_CLUSTER_MASK(fs)); > + if (cluster_freed > free_count) > + cluster_freed = free_count; > + free_count -= cluster_freed; > + free_start += cluster_freed; > + lfree_start += cluster_freed; > + continue; > + } > + free_count--; > + free_start++; > + lfree_start++; I think that this is a little bit excessive. What I think we should do here is to identify first and last partial cluster and possibly call ext2fs_map_cluster_block() for those since we might or might not want to free then depending on whether there are other blocks in it in-use. Then just iterate over the whole clusters in between and free them all. Having to call ext2fs_map_cluster_block() for every single block we're freeing from the extent tree is not really necessary I think especially since we really need to get this information for those possibly partial clusters at the start and end of the extent. Thanks! -Lukas > } > next_extent: > retval = ext2fs_extent_get(handle, op, > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 10, 2013 at 05:53:37PM +0200, Lukáš Czerner wrote: > On Mon, 30 Sep 2013, Darrick J. Wong wrote: > > > Date: Mon, 30 Sep 2013 18:29:03 -0700 > > From: Darrick J. Wong <darrick.wong@oracle.com> > > To: tytso@mit.edu, darrick.wong@oracle.com > > Cc: linux-ext4@vger.kernel.org > > Subject: [PATCH 22/31] libext2fs: During punch, > > only free a cluster if we're sure that all blocks in the cluster are being > > punched > > > > When bigalloc is enabled, using ext2fs_block_alloc_stats2() to free any block > > in a cluster has the effect of freeing the entire cluster. This is problematic > > if a caller instructs us to punch, say, blocks 12-15 of a 16-block cluster, > > because blocks 0-11 now point to a "free" cluster. > > > > The naive way to solve this problem is to see if any of the other blocks in > > this logical cluster map to a physical cluster. If so, then we know that the > > cluster is still in use and it mustn't be freed. Otherwise, we are punching > > the last mapped block in this cluster, so we can free the cluster. > > > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > > --- > > lib/ext2fs/bmap.c | 28 ++++++++++++++++++++++++++++ > > lib/ext2fs/ext2fs.h | 3 +++ > > lib/ext2fs/punch.c | 30 +++++++++++++++++++++++++----- > > 3 files changed, 56 insertions(+), 5 deletions(-) > > > > > > diff --git a/lib/ext2fs/bmap.c b/lib/ext2fs/bmap.c > > index 5074587..a6e35a9 100644 > > --- a/lib/ext2fs/bmap.c > > +++ b/lib/ext2fs/bmap.c > > @@ -173,6 +173,34 @@ static errcode_t implied_cluster_alloc(ext2_filsys fs, ext2_ino_t ino, > > return 0; > > } > > > > +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, > > + struct ext2_inode *inode, blk64_t lblk, > > + blk64_t *pblk) > > +{ > > + ext2_extent_handle_t handle; > > + errcode_t retval; > > + > > + /* Need bigalloc and extents to be enabled */ > > + *pblk = 0; > > + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, > > + EXT4_FEATURE_RO_COMPAT_BIGALLOC) || > > + !(inode->i_flags & EXT4_EXTENTS_FL)) > > + return 0; > > + > > + retval = ext2fs_extent_open2(fs, ino, inode, &handle); > > + if (retval) > > + goto out; > > + > > + retval = implied_cluster_alloc(fs, ino, inode, handle, lblk, pblk); > > + if (retval) > > + goto out2; > > + > > +out2: > > + ext2fs_extent_free(handle); > > +out: > > + return retval; > > +} > > + > > static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino, > > struct ext2_inode *inode, > > ext2_extent_handle_t handle, > > diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h > > index 9fef6d3..88da8db 100644 > > --- a/lib/ext2fs/ext2fs.h > > +++ b/lib/ext2fs/ext2fs.h > > @@ -925,6 +925,9 @@ extern errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, > > struct ext2_inode *inode, > > char *block_buf, int bmap_flags, blk64_t block, > > int *ret_flags, blk64_t *phys_blk); > > +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, > > + struct ext2_inode *inode, blk64_t lblk, > > + blk64_t *pblk); > > > > #if 0 > > /* bmove.c */ > > diff --git a/lib/ext2fs/punch.c b/lib/ext2fs/punch.c > > index 4471f46..e0193b0 100644 > > --- a/lib/ext2fs/punch.c > > +++ b/lib/ext2fs/punch.c > > @@ -183,8 +183,8 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > > ext2_extent_handle_t handle = 0; > > struct ext2fs_extent extent; > > errcode_t retval; > > - blk64_t free_start, next; > > - __u32 free_count, newlen; > > + blk64_t free_start, next, lfree_start, pblk; > > + __u32 free_count, newlen, cluster_freed; > > int freed = 0; > > int op; > > > > @@ -210,6 +210,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > > /* Start of deleted region before extent; > > adjust beginning of extent */ > > free_start = extent.e_pblk; > > + lfree_start = extent.e_lblk; > > if (next > end) > > free_count = end - extent.e_lblk + 1; > > else > > @@ -225,6 +226,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > > dbg_printf("Case #%d\n", 2); > > newlen = start - extent.e_lblk; > > free_start = extent.e_pblk + newlen; > > + lfree_start = extent.e_lblk + newlen; > > free_count = extent.e_len - newlen; > > extent.e_len = newlen; > > } else { > > @@ -240,6 +242,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > > > > extent.e_len = start - extent.e_lblk; > > free_start = extent.e_pblk + extent.e_len; > > + lfree_start = extent.e_lblk + extent.e_len; > > free_count = end - start + 1; > > > > dbg_print_extent("inserting", &newex); > > @@ -280,9 +283,26 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, > > goto errout; > > dbg_printf("Free start %llu, free count = %u\n", > > free_start, free_count); > > - while (free_count-- > 0) { > > - ext2fs_block_alloc_stats2(fs, free_start++, -1); > > - freed++; > > + while (free_count > 0) { > > + retval = ext2fs_map_cluster_block(fs, ino, inode, > > + lfree_start, &pblk); > > + if (retval) > > + goto errout; > > + if (!pblk) { > > + ext2fs_block_alloc_stats2(fs, free_start, -1); > > + freed++; > > + cluster_freed = EXT2FS_CLUSTER_RATIO(fs) - > > + (free_start & EXT2FS_CLUSTER_MASK(fs)); > > + if (cluster_freed > free_count) > > + cluster_freed = free_count; > > + free_count -= cluster_freed; > > + free_start += cluster_freed; > > + lfree_start += cluster_freed; > > + continue; > > + } > > + free_count--; > > + free_start++; > > + lfree_start++; > > I think that this is a little bit excessive. What I think we should > do here is to identify first and last partial cluster and possibly > call ext2fs_map_cluster_block() for those since we might or might > not want to free then depending on whether there are other blocks in > it in-use. > > Then just iterate over the whole clusters in between and free them > all. Having to call ext2fs_map_cluster_block() for every single > block we're freeing from the extent tree is not really necessary I think > especially since we really need to get this information for those > possibly partial clusters at the start and end of the extent. Hmm. I think I could eliminate the middle ext2fs_map_cluster_block() calls by only calling it if free_start is within cluster_ratio blocks of the pre-loop value of free_start, or if free_count < cluster_ratio. I can also split the whole thing into three loops (pre-cluster, clusters, and post-cluster), though for the non-bigalloc case I'd skip to the middle loop. --D > > Thanks! > -Lukas > > > > } > > next_extent: > > retval = ext2fs_extent_get(handle, op, > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/ext2fs/bmap.c b/lib/ext2fs/bmap.c index 5074587..a6e35a9 100644 --- a/lib/ext2fs/bmap.c +++ b/lib/ext2fs/bmap.c @@ -173,6 +173,34 @@ static errcode_t implied_cluster_alloc(ext2_filsys fs, ext2_ino_t ino, return 0; } +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, blk64_t lblk, + blk64_t *pblk) +{ + ext2_extent_handle_t handle; + errcode_t retval; + + /* Need bigalloc and extents to be enabled */ + *pblk = 0; + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, + EXT4_FEATURE_RO_COMPAT_BIGALLOC) || + !(inode->i_flags & EXT4_EXTENTS_FL)) + return 0; + + retval = ext2fs_extent_open2(fs, ino, inode, &handle); + if (retval) + goto out; + + retval = implied_cluster_alloc(fs, ino, inode, handle, lblk, pblk); + if (retval) + goto out2; + +out2: + ext2fs_extent_free(handle); +out: + return retval; +} + static errcode_t extent_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, ext2_extent_handle_t handle, diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h index 9fef6d3..88da8db 100644 --- a/lib/ext2fs/ext2fs.h +++ b/lib/ext2fs/ext2fs.h @@ -925,6 +925,9 @@ extern errcode_t ext2fs_bmap2(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode, char *block_buf, int bmap_flags, blk64_t block, int *ret_flags, blk64_t *phys_blk); +errcode_t ext2fs_map_cluster_block(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, blk64_t lblk, + blk64_t *pblk); #if 0 /* bmove.c */ diff --git a/lib/ext2fs/punch.c b/lib/ext2fs/punch.c index 4471f46..e0193b0 100644 --- a/lib/ext2fs/punch.c +++ b/lib/ext2fs/punch.c @@ -183,8 +183,8 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, ext2_extent_handle_t handle = 0; struct ext2fs_extent extent; errcode_t retval; - blk64_t free_start, next; - __u32 free_count, newlen; + blk64_t free_start, next, lfree_start, pblk; + __u32 free_count, newlen, cluster_freed; int freed = 0; int op; @@ -210,6 +210,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, /* Start of deleted region before extent; adjust beginning of extent */ free_start = extent.e_pblk; + lfree_start = extent.e_lblk; if (next > end) free_count = end - extent.e_lblk + 1; else @@ -225,6 +226,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, dbg_printf("Case #%d\n", 2); newlen = start - extent.e_lblk; free_start = extent.e_pblk + newlen; + lfree_start = extent.e_lblk + newlen; free_count = extent.e_len - newlen; extent.e_len = newlen; } else { @@ -240,6 +242,7 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, extent.e_len = start - extent.e_lblk; free_start = extent.e_pblk + extent.e_len; + lfree_start = extent.e_lblk + extent.e_len; free_count = end - start + 1; dbg_print_extent("inserting", &newex); @@ -280,9 +283,26 @@ static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, goto errout; dbg_printf("Free start %llu, free count = %u\n", free_start, free_count); - while (free_count-- > 0) { - ext2fs_block_alloc_stats2(fs, free_start++, -1); - freed++; + while (free_count > 0) { + retval = ext2fs_map_cluster_block(fs, ino, inode, + lfree_start, &pblk); + if (retval) + goto errout; + if (!pblk) { + ext2fs_block_alloc_stats2(fs, free_start, -1); + freed++; + cluster_freed = EXT2FS_CLUSTER_RATIO(fs) - + (free_start & EXT2FS_CLUSTER_MASK(fs)); + if (cluster_freed > free_count) + cluster_freed = free_count; + free_count -= cluster_freed; + free_start += cluster_freed; + lfree_start += cluster_freed; + continue; + } + free_count--; + free_start++; + lfree_start++; } next_extent: retval = ext2fs_extent_get(handle, op,
When bigalloc is enabled, using ext2fs_block_alloc_stats2() to free any block in a cluster has the effect of freeing the entire cluster. This is problematic if a caller instructs us to punch, say, blocks 12-15 of a 16-block cluster, because blocks 0-11 now point to a "free" cluster. The naive way to solve this problem is to see if any of the other blocks in this logical cluster map to a physical cluster. If so, then we know that the cluster is still in use and it mustn't be freed. Otherwise, we are punching the last mapped block in this cluster, so we can free the cluster. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> --- lib/ext2fs/bmap.c | 28 ++++++++++++++++++++++++++++ lib/ext2fs/ext2fs.h | 3 +++ lib/ext2fs/punch.c | 30 +++++++++++++++++++++++++----- 3 files changed, 56 insertions(+), 5 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html