diff options
Diffstat (limited to 'lib/ext2fs/punch.c')
| -rw-r--r-- | lib/ext2fs/punch.c | 513 |
1 files changed, 513 insertions, 0 deletions
diff --git a/lib/ext2fs/punch.c b/lib/ext2fs/punch.c new file mode 100644 index 0000000..e2543e1 --- /dev/null +++ b/lib/ext2fs/punch.c @@ -0,0 +1,513 @@ +/* + * punch.c --- deallocate blocks allocated to an inode + * + * Copyright (C) 2010 Theodore Ts'o. + * + * %Begin-Header% + * This file may be redistributed under the terms of the GNU Library + * General Public License, version 2. + * %End-Header% + */ + +#include "config.h" +#include <stdio.h> +#include <string.h> +#if HAVE_UNISTD_H +#include <unistd.h> +#endif +#include <errno.h> + +#include "ext2_fs.h" +#include "ext2fs.h" +#include "ext2fsP.h" + +#undef PUNCH_DEBUG + +/* + * This function returns 1 if the specified block is all zeros + */ +static int check_zero_block(char *buf, int blocksize) +{ + char *cp = buf; + int left = blocksize; + + while (left > 0) { + if (*cp++) + return 0; + left--; + } + return 1; +} + +/* + * This clever recursive function handles i_blocks[] as well as + * indirect, double indirect, and triple indirect blocks. It iterates + * over the entries in the i_blocks array or indirect blocks, and for + * each one, will recursively handle any indirect blocks and then + * frees and deallocates the blocks. + */ +static errcode_t ind_punch(ext2_filsys fs, struct ext2_inode *inode, + char *block_buf, blk_t *p, int level, + blk64_t start, blk64_t count, int max) +{ + errcode_t retval; + blk_t b; + int i; + blk64_t offset, incr; + int freed = 0; + +#ifdef PUNCH_DEBUG + printf("Entering ind_punch, level %d, start %llu, count %llu, " + "max %d\n", level, start, count, max); +#endif + incr = 1ULL << ((EXT2_BLOCK_SIZE_BITS(fs->super) - 2) * level); + for (i = 0, offset = 0; i < max; i++, p++, offset += incr) { + if (offset >= start + count) + break; + if (*p == 0 || (offset+incr) <= start) + continue; + b = *p; + if (level > 0) { + blk_t start2; +#ifdef PUNCH_DEBUG + printf("Reading indirect block %u\n", b); +#endif + retval = ext2fs_read_ind_block(fs, b, block_buf); + if (retval) + return retval; + start2 = (start > offset) ? start - offset : 0; + retval = ind_punch(fs, inode, block_buf + fs->blocksize, + (blk_t *) block_buf, level - 1, + start2, count - offset, + fs->blocksize >> 2); + if (retval) + return retval; + retval = ext2fs_write_ind_block(fs, b, block_buf); + if (retval) + return retval; + if (!check_zero_block(block_buf, fs->blocksize)) + continue; + } +#ifdef PUNCH_DEBUG + printf("Freeing block %u (offset %llu)\n", b, offset); +#endif + ext2fs_block_alloc_stats(fs, b, -1); + *p = 0; + freed++; + } +#ifdef PUNCH_DEBUG + printf("Freed %d blocks\n", freed); +#endif + return ext2fs_iblk_sub_blocks(fs, inode, freed); +} + +#define BLK_T_MAX ((blk_t)~0ULL) +static errcode_t ext2fs_punch_ind(ext2_filsys fs, struct ext2_inode *inode, + char *block_buf, blk64_t start, blk64_t end) +{ + errcode_t retval; + char *buf = 0; + int level; + int num = EXT2_NDIR_BLOCKS; + blk_t *bp = inode->i_block; + blk_t addr_per_block; + blk64_t max = EXT2_NDIR_BLOCKS; + blk_t count; + + /* Check start/end don't overflow the 2^32-1 indirect block limit */ + if (start > BLK_T_MAX) + return 0; + if (end >= BLK_T_MAX || end - start + 1 >= BLK_T_MAX) + count = BLK_T_MAX - start; + else + count = end - start + 1; + + if (!block_buf) { + retval = ext2fs_get_array(3, fs->blocksize, &buf); + if (retval) + return retval; + block_buf = buf; + } + + addr_per_block = (blk_t)fs->blocksize >> 2; + + for (level = 0; level < 4; level++, max *= (blk64_t)addr_per_block) { +#ifdef PUNCH_DEBUG + printf("Main loop level %d, start %llu count %u " + "max %llu num %d\n", level, start, count, max, num); +#endif + if (start < max) { + retval = ind_punch(fs, inode, block_buf, bp, level, + start, count, num); + if (retval) + goto errout; + if (count > max) + count -= max - start; + else + break; + start = 0; + } else + start -= max; + bp += num; + if (level == 0) { + num = 1; + max = 1; + } + } + retval = 0; +errout: + if (buf) + ext2fs_free_mem(&buf); + return retval; +} +#undef BLK_T_MAX + +#ifdef PUNCH_DEBUG + +#define dbg_printf(f, a...) printf(f, ## a) + +static void dbg_print_extent(char *desc, struct ext2fs_extent *extent) +{ + if (desc) + printf("%s: ", desc); + printf("extent: lblk %llu--%llu, len %u, pblk %llu, flags: ", + extent->e_lblk, extent->e_lblk + extent->e_len - 1, + extent->e_len, extent->e_pblk); + if (extent->e_flags & EXT2_EXTENT_FLAGS_LEAF) + fputs("LEAF ", stdout); + if (extent->e_flags & EXT2_EXTENT_FLAGS_UNINIT) + fputs("UNINIT ", stdout); + if (extent->e_flags & EXT2_EXTENT_FLAGS_SECOND_VISIT) + fputs("2ND_VISIT ", stdout); + if (!extent->e_flags) + fputs("(none)", stdout); + fputc('\n', stdout); + +} +#else +#define dbg_print_extent(desc, ex) do { } while (0) +#define dbg_printf(f, a...) do { } while (0) +#endif + +/* Free a range of blocks, respecting cluster boundaries */ +static errcode_t punch_extent_blocks(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, + blk64_t lfree_start, blk64_t free_start, + __u32 free_count, int *freed) +{ + blk64_t pblk; + int freed_now = 0; + __u32 cluster_freed; + errcode_t retval = 0; + + if (free_start < fs->super->s_first_data_block || + (free_start + free_count) >= ext2fs_blocks_count(fs->super)) + return EXT2_ET_BAD_BLOCK_NUM; + + /* No bigalloc? Just free each block. */ + if (EXT2FS_CLUSTER_RATIO(fs) == 1) { + *freed += free_count; + while (free_count-- > 0) + ext2fs_block_alloc_stats2(fs, free_start++, -1); + return retval; + } + + /* + * Try to free up to the next cluster boundary. We assume that all + * blocks in a logical cluster map to blocks from the same physical + * cluster, and that the offsets within the [pl]clusters match. + */ + if (free_start & EXT2FS_CLUSTER_MASK(fs)) { + 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_now++; + } + 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; + } + + /* Free whole clusters from the middle of the range. */ + while (free_count > 0 && free_count >= (unsigned) EXT2FS_CLUSTER_RATIO(fs)) { + ext2fs_block_alloc_stats2(fs, free_start, -1); + freed_now++; + cluster_freed = EXT2FS_CLUSTER_RATIO(fs); + free_count -= cluster_freed; + free_start += cluster_freed; + lfree_start += cluster_freed; + } + + /* Try to free the last cluster. */ + if (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_now++; + } + } + +errout: + *freed += freed_now; + return retval; +} + +static errcode_t ext2fs_punch_extent(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, + blk64_t start, blk64_t end) +{ + ext2_extent_handle_t handle = 0; + struct ext2fs_extent extent; + errcode_t retval; + blk64_t free_start, next, lfree_start; + __u32 free_count, newlen; + int freed = 0; + int op; + + retval = ext2fs_extent_open2(fs, ino, inode, &handle); + if (retval) + return retval; + /* + * Find the extent closest to the start of the punch range. We don't + * check the return value because _goto() sets the current node to the + * next-lowest extent if 'start' is in a hole, and doesn't set a + * current node if there was a real error reading the extent tree. + * In that case, _get() will error out. + * + * Note: If _get() returns 'no current node', that simply means that + * there aren't any blocks mapped past this point in the file, so we're + * done. + */ + ext2fs_extent_goto(handle, start); + retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent); + if (retval == EXT2_ET_NO_CURRENT_NODE) { + retval = 0; + goto errout; + } else if (retval) + goto errout; + while (1) { + op = EXT2_EXTENT_NEXT_LEAF; + dbg_print_extent("main loop", &extent); + next = extent.e_lblk + extent.e_len; + dbg_printf("start %llu, end %llu, next %llu\n", + (unsigned long long) start, + (unsigned long long) end, + (unsigned long long) next); + if (start <= extent.e_lblk) { + /* + * Have we iterated past the end of the punch region? + * If so, we can stop. + */ + if (end < extent.e_lblk) + break; + dbg_printf("Case #%d\n", 1); + /* 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 + free_count = extent.e_len; + extent.e_len -= free_count; + extent.e_lblk += free_count; + extent.e_pblk += free_count; + } else if (end >= next-1) { + /* + * Is the punch region beyond this extent? This can + * happen if start is already inside a hole. Try to + * advance to the next extent if this is the case. + */ + if (start >= next) + goto next_extent; + /* End of deleted region after extent; + adjust end of extent */ + 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 { + struct ext2fs_extent newex; + + dbg_printf("Case #%d\n", 3); + /* The hard case; we need to split the extent */ + newex.e_pblk = extent.e_pblk + + (end + 1 - extent.e_lblk); + newex.e_lblk = end + 1; + newex.e_len = next - end - 1; + newex.e_flags = extent.e_flags; + + 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); + retval = ext2fs_extent_insert(handle, + EXT2_EXTENT_INSERT_AFTER, &newex); + if (retval) + goto errout; + retval = ext2fs_extent_fix_parents(handle); + if (retval) + goto errout; + /* + * Now pointing at inserted extent; so go back. + * + * We cannot use EXT2_EXTENT_PREV to go back; note the + * subtlety in the comment for fix_parents(). + */ + retval = ext2fs_extent_goto(handle, extent.e_lblk); + if (retval) + goto errout; + } + if (extent.e_len) { + dbg_print_extent("replacing", &extent); + retval = ext2fs_extent_replace(handle, 0, &extent); + if (retval) + goto errout; + retval = ext2fs_extent_fix_parents(handle); + } else { + struct ext2fs_extent newex; + blk64_t old_lblk, next_lblk; + dbg_printf("deleting current extent%s\n", ""); + + /* + * Save the location of the next leaf, then slip + * back to the current extent. + */ + retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, + &newex); + if (retval) + goto errout; + old_lblk = newex.e_lblk; + + retval = ext2fs_extent_get(handle, + EXT2_EXTENT_NEXT_LEAF, + &newex); + if (retval == EXT2_ET_EXTENT_NO_NEXT) + next_lblk = old_lblk; + else if (retval) + goto errout; + else + next_lblk = newex.e_lblk; + + retval = ext2fs_extent_goto(handle, old_lblk); + if (retval) + goto errout; + + /* Now delete the extent. */ + retval = ext2fs_extent_delete(handle, 0); + if (retval) + goto errout; + + retval = ext2fs_extent_fix_parents(handle); + if (retval && retval != EXT2_ET_NO_CURRENT_NODE) + goto errout; + retval = 0; + + /* + * Jump forward to the next extent. If there are + * errors, the ext2fs_extent_get down below will + * capture them for us. + */ + (void)ext2fs_extent_goto(handle, next_lblk); + op = EXT2_EXTENT_CURRENT; + } + if (retval) + goto errout; + dbg_printf("Free start %llu, free count = %u\n", + free_start, free_count); + retval = punch_extent_blocks(fs, ino, inode, lfree_start, + free_start, free_count, &freed); + if (retval) + goto errout; + next_extent: + retval = ext2fs_extent_get(handle, op, + &extent); + if (retval == EXT2_ET_EXTENT_NO_NEXT || + retval == EXT2_ET_NO_CURRENT_NODE) + break; + if (retval) + goto errout; + } + dbg_printf("Freed %d blocks\n", freed); + retval = ext2fs_iblk_sub_blocks(fs, inode, freed); +errout: + ext2fs_extent_free(handle); + return retval; +} + +static errcode_t ext2fs_punch_inline_data(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, + blk64_t start, + blk64_t end EXT2FS_ATTR((unused))) +{ + errcode_t retval; + + /* + * In libext2fs ext2fs_punch is based on block unit. So that + * means that if start > 0 we don't need to do nothing. Due + * to this we will remove all inline data in ext2fs_punch() + * now. + */ + if (start > 0) + return 0; + + memset((char *)inode->i_block, 0, EXT4_MIN_INLINE_DATA_SIZE); + inode->i_size = 0; + retval = ext2fs_write_inode(fs, ino, inode); + if (retval) + return retval; + + return ext2fs_inline_data_ea_remove(fs, ino); +} + +/* + * Deallocate all logical _blocks_ starting at start to end, inclusive. + * If end is ~0ULL, then this is effectively truncate. + */ +errcode_t ext2fs_punch(ext2_filsys fs, ext2_ino_t ino, + struct ext2_inode *inode, + char *block_buf, blk64_t start, + blk64_t end) +{ + errcode_t retval; + struct ext2_inode inode_buf; + + if (start > end) + return EINVAL; + + /* Read inode structure if necessary */ + if (!inode) { + retval = ext2fs_read_inode(fs, ino, &inode_buf); + if (retval) + return retval; + inode = &inode_buf; + } + if (inode->i_flags & EXT4_INLINE_DATA_FL) + return ext2fs_punch_inline_data(fs, ino, inode, start, end); + else if (inode->i_flags & EXT4_EXTENTS_FL) + retval = ext2fs_punch_extent(fs, ino, inode, start, end); + else + retval = ext2fs_punch_ind(fs, inode, block_buf, start, end); + if (retval) + return retval; + +#ifdef PUNCH_DEBUG + printf("%u: write inode size now %lu blocks %u\n", + ino, EXT2_I_SIZE(inode), inode->i_blocks); +#endif + return ext2fs_write_inode(fs, ino, inode); +} |