mirror of https://github.com/vitalif/e2fsprogs
libext2fs: Avoid creating unneeded new extents in ext2fs_extent_set_bmap()
Avoiding inserting a new extent if it is possible to merge the new block to the beginning or the end of the previous or next extent. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>bitmap-optimize
parent
64cb68b3ea
commit
8b5ed492de
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@ -1146,11 +1146,14 @@ errcode_t ext2fs_extent_set_bmap(ext2_extent_handle_t handle,
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int mapped = 1; /* logical is mapped? */
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int orig_height;
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int extent_uninit = 0;
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int prev_uninit = 0;
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int next_uninit = 0;
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int new_uninit = 0;
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int max_len = EXT_INIT_MAX_LEN;
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int has_prev, has_next;
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blk64_t orig_lblk;
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struct extent_path *path;
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struct ext2fs_extent extent;
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struct ext2fs_extent extent, next_extent, prev_extent;
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struct ext2fs_extent newextent;
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struct ext2_extent_info info;
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@ -1222,12 +1225,44 @@ errcode_t ext2fs_extent_set_bmap(ext2_extent_handle_t handle,
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/*
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* This may be the extent *before* the requested logical,
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* if it's currently unmapped.
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*
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* Get the previous and next leaf extents, if they are present.
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*/
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retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, &extent);
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if (retval)
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goto done;
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if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
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extent_uninit = 1;
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retval = ext2fs_extent_get(handle, EXT2_EXTENT_NEXT_LEAF, &next_extent);
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if (retval) {
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has_next = 0;
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if (retval != EXT2_ET_EXTENT_NO_NEXT)
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goto done;
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} else {
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dbg_print_extent("set_bmap: next_extent",
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&next_extent);
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has_next = 1;
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if (next_extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
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next_uninit = 1;
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}
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retval = ext2fs_extent_goto(handle, logical);
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if (retval && retval != EXT2_ET_EXTENT_NOT_FOUND)
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goto done;
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retval = ext2fs_extent_get(handle, EXT2_EXTENT_PREV_LEAF, &prev_extent);
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if (retval) {
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has_prev = 0;
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if (retval != EXT2_ET_EXTENT_NO_PREV)
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goto done;
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} else {
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has_prev = 1;
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dbg_print_extent("set_bmap: prev_extent",
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&prev_extent);
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if (prev_extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
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prev_uninit = 1;
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}
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retval = ext2fs_extent_goto(handle, logical);
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if (retval && retval != EXT2_ET_EXTENT_NOT_FOUND)
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goto done;
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/* check if already pointing to the requested physical */
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if (mapped && (new_uninit == extent_uninit) &&
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@ -1248,6 +1283,28 @@ errcode_t ext2fs_extent_set_bmap(ext2_extent_handle_t handle,
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((int) extent.e_len < max_len-1)) {
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extent.e_len++;
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retval = ext2fs_extent_replace(handle, 0, &extent);
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} else if ((logical == extent.e_lblk - 1) &&
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(physical == extent.e_pblk - 1) &&
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(new_uninit == extent_uninit) &&
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((int) extent.e_len < max_len - 1)) {
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extent.e_len++;
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extent.e_lblk--;
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extent.e_pblk--;
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retval = ext2fs_extent_replace(handle, 0, &extent);
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} else if (has_next &&
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(logical == next_extent.e_lblk - 1) &&
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(physical == next_extent.e_pblk - 1) &&
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(new_uninit == next_uninit) &&
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((int) next_extent.e_len < max_len - 1)) {
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retval = ext2fs_extent_get(handle,
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EXT2_EXTENT_NEXT_LEAF,
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&next_extent);
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if (retval)
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goto done;
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next_extent.e_len++;
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next_extent.e_lblk--;
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next_extent.e_pblk--;
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retval = ext2fs_extent_replace(handle, 0, &next_extent);
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} else if (logical < extent.e_lblk)
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retval = ext2fs_extent_insert(handle, 0, &newextent);
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else
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@ -1279,14 +1336,32 @@ errcode_t ext2fs_extent_set_bmap(ext2_extent_handle_t handle,
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#ifdef DEBUG
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printf("(re/un)mapping last block in extent\n");
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#endif
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/* Make sure insert works before replacing old extent */
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if (physical) {
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if (has_next &&
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(logical == (next_extent.e_lblk - 1)) &&
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(physical == (next_extent.e_pblk - 1)) &&
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(new_uninit == next_uninit) &&
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((int) next_extent.e_len < max_len - 1)) {
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retval = ext2fs_extent_get(handle,
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EXT2_EXTENT_NEXT_LEAF, &next_extent);
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if (retval)
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goto done;
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next_extent.e_len++;
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next_extent.e_lblk--;
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next_extent.e_pblk--;
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retval = ext2fs_extent_replace(handle, 0,
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&next_extent);
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if (retval)
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goto done;
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} else
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retval = ext2fs_extent_insert(handle,
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EXT2_EXTENT_INSERT_AFTER, &newextent);
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if (retval)
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goto done;
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/* Now pointing at inserted extent; move back to prev */
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retval = ext2fs_extent_goto(handle, logical - 1);
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retval = ext2fs_extent_get(handle,
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EXT2_EXTENT_PREV_LEAF,
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&extent);
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if (retval)
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goto done;
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}
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@ -1299,30 +1374,23 @@ errcode_t ext2fs_extent_set_bmap(ext2_extent_handle_t handle,
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printf("(re/un)mapping first block in extent\n");
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#endif
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if (physical) {
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if (has_prev &&
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(logical == (prev_extent.e_lblk +
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prev_extent.e_len)) &&
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(physical == (prev_extent.e_pblk +
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prev_extent.e_len)) &&
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(new_uninit == prev_uninit) &&
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((int) prev_extent.e_len < max_len-1)) {
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retval = ext2fs_extent_get(handle,
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EXT2_EXTENT_PREV_LEAF,
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&extent);
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if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
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extent_uninit = 1;
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if (retval == EXT2_ET_EXTENT_NO_PREV) {
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retval = ext2fs_extent_goto(handle, logical);
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EXT2_EXTENT_PREV_LEAF, &prev_extent);
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if (retval)
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goto done;
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prev_extent.e_len++;
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retval = ext2fs_extent_replace(handle, 0,
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&prev_extent);
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} else
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retval = ext2fs_extent_insert(handle,
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0, &newextent);
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} else if (retval)
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goto done;
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else if ((logical == extent.e_lblk + extent.e_len) &&
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(physical == extent.e_pblk + extent.e_len) &&
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(new_uninit == extent_uninit) &&
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((int) extent.e_len < max_len-1)) {
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extent.e_len++;
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retval = ext2fs_extent_replace(handle, 0,
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&extent);
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} else {
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retval = ext2fs_extent_insert(handle,
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EXT2_EXTENT_INSERT_AFTER, &newextent);
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}
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if (retval)
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goto done;
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retval = ext2fs_extent_get(handle,
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