diff options
| -rw-r--r-- | Documentation/btrfs-filesystem.asciidoc | 4 | ||||
| -rw-r--r-- | cmds-filesystem.c | 255 | ||||
| -rw-r--r-- | ctree.h | 3 | ||||
| -rwxr-xr-x | tests/misc-tests.sh | 2 | ||||
| -rwxr-xr-x | tests/misc-tests/004-shrink-fs/test.sh | 69 |
5 files changed, 331 insertions, 2 deletions
diff --git a/Documentation/btrfs-filesystem.asciidoc b/Documentation/btrfs-filesystem.asciidoc index 31cd51be..2b34242d 100644 --- a/Documentation/btrfs-filesystem.asciidoc +++ b/Documentation/btrfs-filesystem.asciidoc @@ -93,7 +93,7 @@ If a newlabel optional argument is passed, the label is changed. NOTE: the maximum allowable length shall be less than 256 chars // Some wording are extracted by the resize2fs man page -*resize* [<devid>:][+/-]<size>[kKmMgGtTpPeE]|[<devid>:]max <path>:: +*resize* [<devid>:][+/-]<size>[kKmMgGtTpPeE]|[<devid>:]max|[<devid>:]get_min_size <path>:: Resize a mounted filesystem identified by directory <path>. A particular device can be resized by specifying a <devid>. + @@ -113,6 +113,8 @@ KiB, MiB, GiB, TiB, PiB, or EiB, respectively. Case does not matter. + If \'max' is passed, the filesystem will occupy all available space on the device devid. +If \'get_min_size' is passed, return the minimum size the device can be +shrunk to, without performing any resize operation. + The resize command does not manipulate the size of underlying partition. If you wish to enlarge/reduce a filesystem, you must make sure you diff --git a/cmds-filesystem.c b/cmds-filesystem.c index 800aa4dc..b44a6553 100644 --- a/cmds-filesystem.c +++ b/cmds-filesystem.c @@ -1271,14 +1271,264 @@ static int cmd_defrag(int argc, char **argv) } static const char * const cmd_resize_usage[] = { - "btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max <path>", + "btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max|[devid:]get_min_size <path>", "Resize a filesystem", "If 'max' is passed, the filesystem will occupy all available space", "on the device 'devid'.", + "If 'get_min_size' is passed, return the minimum size the device can", + "be shrunk to.", "[kK] means KiB, which denotes 1KiB = 1024B, 1MiB = 1024KiB, etc.", NULL }; +struct dev_extent_elem { + u64 start; + /* inclusive end */ + u64 end; + struct list_head list; +}; + +static int add_dev_extent(struct list_head *list, + const u64 start, const u64 end, + const int append) +{ + struct dev_extent_elem *e; + + e = malloc(sizeof(*e)); + if (!e) + return -ENOMEM; + + e->start = start; + e->end = end; + + if (append) + list_add_tail(&e->list, list); + else + list_add(&e->list, list); + + return 0; +} + +static void free_dev_extent_list(struct list_head *list) +{ + while (!list_empty(list)) { + struct dev_extent_elem *e; + + e = list_first_entry(list, struct dev_extent_elem, list); + list_del(&e->list); + free(e); + } +} + +static int hole_includes_sb_mirror(const u64 start, const u64 end) +{ + int i; + int ret = 0; + + for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) { + u64 bytenr = btrfs_sb_offset(i); + + if (bytenr >= start && bytenr <= end) { + ret = 1; + break; + } + } + + return ret; +} + +static void adjust_dev_min_size(struct list_head *extents, + struct list_head *holes, + u64 *min_size) +{ + /* + * If relocation of the block group of a device extent must happen (see + * below) scratch space is used for the relocation. So track here the + * size of the largest device extent that has to be relocated. We track + * only the largest and not the sum of the sizes of all relocated block + * groups because after each block group is relocated the running + * transaction is committed so that pinned space is released. + */ + u64 scratch_space = 0; + + /* + * List of device extents is sorted by descending order of the extent's + * end offset. If some extent goes beyond the computed minimum size, + * which initially matches the sum of the lenghts of all extents, + * we need to check if the extent can be relocated to an hole in the + * device between [0, *min_size[ (which is what the resize ioctl does). + */ + while (!list_empty(extents)) { + struct dev_extent_elem *e; + struct dev_extent_elem *h; + int found = 0; + u64 extent_len; + u64 hole_len = 0; + + e = list_first_entry(extents, struct dev_extent_elem, list); + if (e->end <= *min_size) + break; + + /* + * Our extent goes beyond the computed *min_size. See if we can + * find a hole large enough to relocate it to. If not we must stop + * and set *min_size to the end of the extent. + */ + extent_len = e->end - e->start + 1; + list_for_each_entry(h, holes, list) { + hole_len = h->end - h->start + 1; + if (hole_len >= extent_len) { + found = 1; + break; + } + } + + if (!found) { + *min_size = e->end + 1; + break; + } + + /* + * If the hole found contains the location for a superblock + * mirror, we are pessimistic and require allocating one + * more extent of the same size. This is because the block + * group could be in the worst case used by a single extent + * with a size >= (block_group.length - superblock.size). + */ + if (hole_includes_sb_mirror(h->start, + h->start + extent_len - 1)) + *min_size += extent_len; + + if (hole_len > extent_len) { + h->start += extent_len; + } else { + list_del(&h->list); + free(h); + } + + list_del(&e->list); + free(e); + + if (extent_len > scratch_space) + scratch_space = extent_len; + } + + if (scratch_space) { + *min_size += scratch_space; + /* + * Chunk allocation requires inserting/updating items in the + * chunk tree, so often this can lead to the need of allocating + * a new system chunk too, which has a maximum size of 32Mb. + */ + *min_size += 32 * 1024 * 1024; + } +} + +static int get_min_size(int fd, DIR *dirstream, const char *amount) +{ + int ret = 1; + char *p = strstr(amount, ":"); + u64 devid = 1; + /* + * Device allocations starts at 1Mb or at the value passed through the + * mount option alloc_start if it's bigger than 1Mb. The alloc_start + * option is used for debugging and testing only, and recently the + * possibility of deprecating/removing it has been discussed, so we + * ignore it here. + */ + u64 min_size = 1 * 1024 * 1024ull; + struct btrfs_ioctl_search_args args; + struct btrfs_ioctl_search_key *sk = &args.key; + u64 last_pos = (u64)-1; + LIST_HEAD(extents); + LIST_HEAD(holes); + + if (p && sscanf(amount, "%llu:get_min_size", &devid) != 1) { + fprintf(stderr, "Invalid parameter: %s\n", amount); + goto out; + } + + memset(&args, 0, sizeof(args)); + sk->tree_id = BTRFS_DEV_TREE_OBJECTID; + sk->min_objectid = devid; + sk->max_objectid = devid; + sk->max_type = BTRFS_DEV_EXTENT_KEY; + sk->min_type = BTRFS_DEV_EXTENT_KEY; + sk->min_offset = 0; + sk->max_offset = (u64)-1; + sk->min_transid = 0; + sk->max_transid = (u64)-1; + sk->nr_items = 4096; + + while (1) { + int i; + struct btrfs_ioctl_search_header *sh; + unsigned long off = 0; + + ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args); + if (ret < 0) { + fprintf(stderr, + "Error invoking tree search ioctl: %s\n", + strerror(errno)); + ret = 1; + goto out; + } + + if (sk->nr_items == 0) + break; + + for (i = 0; i < sk->nr_items; i++) { + struct btrfs_dev_extent *extent; + u64 len; + + sh = (struct btrfs_ioctl_search_header *)(args.buf + + off); + off += sizeof(*sh); + extent = (struct btrfs_dev_extent *)(args.buf + off); + off += sh->len; + + sk->min_objectid = sh->objectid; + sk->min_type = sh->type; + sk->min_offset = sh->offset + 1; + + if (sh->objectid != devid || + sh->type != BTRFS_DEV_EXTENT_KEY) + continue; + + len = btrfs_stack_dev_extent_length(extent); + min_size += len; + ret = add_dev_extent(&extents, sh->offset, + sh->offset + len - 1, 0); + + if (!ret && last_pos != (u64)-1 && + last_pos != sh->offset) + ret = add_dev_extent(&holes, last_pos, + sh->offset - 1, 1); + if (ret) { + fprintf(stderr, "Error: %s\n", strerror(-ret)); + ret = 1; + goto out; + } + + last_pos = sh->offset + len; + } + + if (sk->min_type != BTRFS_DEV_EXTENT_KEY || + sk->min_objectid != devid) + break; + } + + adjust_dev_min_size(&extents, &holes, &min_size); + printf("%llu bytes (%s)\n", min_size, pretty_size(min_size)); + ret = 0; +out: + close_file_or_dir(fd, dirstream); + free_dev_extent_list(&extents); + free_dev_extent_list(&holes); + + return ret; +} + static int cmd_resize(int argc, char **argv) { struct btrfs_ioctl_vol_args args; @@ -1320,6 +1570,9 @@ static int cmd_resize(int argc, char **argv) return 1; } + if (strstr(amount, "get_min_size")) + return get_min_size(fd, dirstream, amount); + printf("Resize '%s' of '%s'\n", path, amount); memset(&args, 0, sizeof(args)); strncpy_null(args.name, amount); @@ -1491,6 +1491,9 @@ BTRFS_SETGET_FUNCS(dev_extent_chunk_offset, struct btrfs_dev_extent, chunk_offset, 64); BTRFS_SETGET_FUNCS(dev_extent_length, struct btrfs_dev_extent, length, 64); +BTRFS_SETGET_STACK_FUNCS(stack_dev_extent_length, struct btrfs_dev_extent, + length, 64); + static inline u8 *btrfs_dev_extent_chunk_tree_uuid(struct btrfs_dev_extent *dev) { unsigned long ptr = offsetof(struct btrfs_dev_extent, chunk_tree_uuid); diff --git a/tests/misc-tests.sh b/tests/misc-tests.sh index 5bbe9140..2ae99db9 100755 --- a/tests/misc-tests.sh +++ b/tests/misc-tests.sh @@ -20,6 +20,8 @@ export RESULTS # For custom script needs to verfiy recovery export TEST_MNT export LANG +# For tests that only use a loop device +export IMAGE rm -f $RESULTS mkdir -p $TEST_MNT || _fail "unable to create mount point on $TEST_MNT" diff --git a/tests/misc-tests/004-shrink-fs/test.sh b/tests/misc-tests/004-shrink-fs/test.sh new file mode 100755 index 00000000..393cccf5 --- /dev/null +++ b/tests/misc-tests/004-shrink-fs/test.sh @@ -0,0 +1,69 @@ +#!/bin/bash +# +# Test getting the minimum size a filesystem can be resized to and verify we +# are able to resize (shrink) it to that size. +# + +source $TOP/tests/common + +check_prereq mkfs.btrfs +setup_root_helper + +shrink_test() +{ + min_size=$($SUDO_HELPER $TOP/btrfs filesystem resize get_min_size $TEST_MNT) + if [ $? != 0 ]; then + _fail "Failed to get minimum size" + fi + min_size=$(echo $min_size | cut -d ' ' -f 1) + echo "min size = ${min_size}" >> $RESULTS + run_check $SUDO_HELPER $TOP/btrfs filesystem resize $min_size $TEST_MNT +} + +run_check truncate -s 20G $IMAGE +run_check $TOP/mkfs.btrfs -f $IMAGE +run_check $SUDO_HELPER mount $IMAGE $TEST_MNT +run_check $SUDO_HELPER chmod a+rw $TEST_MNT + +# Create 7 data block groups, each with a size of 1Gb. +for ((i = 1; i <= 7; i++)); do + run_check fallocate -l 1G $TEST_MNT/foo$i +done + +# Make sure they are persisted (all the chunk, device and block group items +# added to the chunk/dev/extent trees). +run_check $TOP/btrfs filesystem sync $TEST_MNT + +# Now remove 3 of those 1G files. This will result in 3 block groups becoming +# unused, which will be automatically deleted by the cleaner kthread, and this +# will result in 3 holes (unallocated space) in the device (each with a size +# of 1Gb). + +run_check rm -f $TEST_MNT/foo2 +run_check rm -f $TEST_MNT/foo4 +run_check rm -f $TEST_MNT/foo6 + +# Sync once to wake up the cleaner kthread which will delete the unused block +# groups - it could have been sleeping when they became unused. Then wait a bit +# to allow the cleaner kthread to delete them and then finally ensure the +# transaction started by the cleaner kthread is committed. +run_check $TOP/btrfs filesystem sync $TEST_MNT +sleep 3 +run_check $TOP/btrfs filesystem sync $TEST_MNT + +# Now attempt to get the minimum size we can resize the filesystem to and verify +# the resize operation succeeds. This size closely matches the sum of the size +# of all the allocated device extents. +for ((i = 1; i <= 3; i++)); do + shrink_test +done + +# Now convert metadata and system chunks to the single profile and check we are +# still able to get a correct minimum size and shrink to that size. +run_check $SUDO_HELPER $TOP/btrfs balance start -mconvert=single \ + -sconvert=single -f $TEST_MNT +for ((i = 1; i <= 3; i++)); do + shrink_test +done + +run_check $SUDO_HELPER umount $TEST_MNT |