diff options
author | Dave Kleikamp <shaggy@austin.ibm.com> | 2006-10-11 01:20:50 -0700 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-11 11:14:15 -0700 |
commit | ac27a0ec112a089f1a5102bc8dffc79c8c815571 (patch) | |
tree | bcbcc0a5a88bf99b35119d9d9d660a37c503d787 /fs/ext4/balloc.c | |
parent | 502717f4e112b18d9c37753a32f675bec9f2838b (diff) |
[PATCH] ext4: initial copy of files from ext3
Start of the ext4 patch series. See Documentation/filesystems/ext4.txt for
details.
This is a simple copy of the files in fs/ext3 to fs/ext4 and
/usr/incude/linux/ext3* to /usr/include/ex4*
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/ext4/balloc.c')
-rw-r--r-- | fs/ext4/balloc.c | 1818 |
1 files changed, 1818 insertions, 0 deletions
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c new file mode 100644 index 000000000000..b41a7d7e20f0 --- /dev/null +++ b/fs/ext4/balloc.c @@ -0,0 +1,1818 @@ +/* + * linux/fs/ext3/balloc.c + * + * Copyright (C) 1992, 1993, 1994, 1995 + * Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993 + * Big-endian to little-endian byte-swapping/bitmaps by + * David S. Miller (davem@caip.rutgers.edu), 1995 + */ + +#include <linux/time.h> +#include <linux/capability.h> +#include <linux/fs.h> +#include <linux/jbd.h> +#include <linux/ext3_fs.h> +#include <linux/ext3_jbd.h> +#include <linux/quotaops.h> +#include <linux/buffer_head.h> + +/* + * balloc.c contains the blocks allocation and deallocation routines + */ + +/* + * The free blocks are managed by bitmaps. A file system contains several + * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap + * block for inodes, N blocks for the inode table and data blocks. + * + * The file system contains group descriptors which are located after the + * super block. Each descriptor contains the number of the bitmap block and + * the free blocks count in the block. The descriptors are loaded in memory + * when a file system is mounted (see ext3_read_super). + */ + + +#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1) + +/** + * ext3_get_group_desc() -- load group descriptor from disk + * @sb: super block + * @block_group: given block group + * @bh: pointer to the buffer head to store the block + * group descriptor + */ +struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb, + unsigned int block_group, + struct buffer_head ** bh) +{ + unsigned long group_desc; + unsigned long offset; + struct ext3_group_desc * desc; + struct ext3_sb_info *sbi = EXT3_SB(sb); + + if (block_group >= sbi->s_groups_count) { + ext3_error (sb, "ext3_get_group_desc", + "block_group >= groups_count - " + "block_group = %d, groups_count = %lu", + block_group, sbi->s_groups_count); + + return NULL; + } + smp_rmb(); + + group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb); + offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1); + if (!sbi->s_group_desc[group_desc]) { + ext3_error (sb, "ext3_get_group_desc", + "Group descriptor not loaded - " + "block_group = %d, group_desc = %lu, desc = %lu", + block_group, group_desc, offset); + return NULL; + } + + desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data; + if (bh) + *bh = sbi->s_group_desc[group_desc]; + return desc + offset; +} + +/** + * read_block_bitmap() + * @sb: super block + * @block_group: given block group + * + * Read the bitmap for a given block_group, reading into the specified + * slot in the superblock's bitmap cache. + * + * Return buffer_head on success or NULL in case of failure. + */ +static struct buffer_head * +read_block_bitmap(struct super_block *sb, unsigned int block_group) +{ + struct ext3_group_desc * desc; + struct buffer_head * bh = NULL; + + desc = ext3_get_group_desc (sb, block_group, NULL); + if (!desc) + goto error_out; + bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap)); + if (!bh) + ext3_error (sb, "read_block_bitmap", + "Cannot read block bitmap - " + "block_group = %d, block_bitmap = %u", + block_group, le32_to_cpu(desc->bg_block_bitmap)); +error_out: + return bh; +} +/* + * The reservation window structure operations + * -------------------------------------------- + * Operations include: + * dump, find, add, remove, is_empty, find_next_reservable_window, etc. + * + * We use a red-black tree to represent per-filesystem reservation + * windows. + * + */ + +/** + * __rsv_window_dump() -- Dump the filesystem block allocation reservation map + * @rb_root: root of per-filesystem reservation rb tree + * @verbose: verbose mode + * @fn: function which wishes to dump the reservation map + * + * If verbose is turned on, it will print the whole block reservation + * windows(start, end). Otherwise, it will only print out the "bad" windows, + * those windows that overlap with their immediate neighbors. + */ +#if 1 +static void __rsv_window_dump(struct rb_root *root, int verbose, + const char *fn) +{ + struct rb_node *n; + struct ext3_reserve_window_node *rsv, *prev; + int bad; + +restart: + n = rb_first(root); + bad = 0; + prev = NULL; + + printk("Block Allocation Reservation Windows Map (%s):\n", fn); + while (n) { + rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node); + if (verbose) + printk("reservation window 0x%p " + "start: %lu, end: %lu\n", + rsv, rsv->rsv_start, rsv->rsv_end); + if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) { + printk("Bad reservation %p (start >= end)\n", + rsv); + bad = 1; + } + if (prev && prev->rsv_end >= rsv->rsv_start) { + printk("Bad reservation %p (prev->end >= start)\n", + rsv); + bad = 1; + } + if (bad) { + if (!verbose) { + printk("Restarting reservation walk in verbose mode\n"); + verbose = 1; + goto restart; + } + } + n = rb_next(n); + prev = rsv; + } + printk("Window map complete.\n"); + if (bad) + BUG(); +} +#define rsv_window_dump(root, verbose) \ + __rsv_window_dump((root), (verbose), __FUNCTION__) +#else +#define rsv_window_dump(root, verbose) do {} while (0) +#endif + +/** + * goal_in_my_reservation() + * @rsv: inode's reservation window + * @grp_goal: given goal block relative to the allocation block group + * @group: the current allocation block group + * @sb: filesystem super block + * + * Test if the given goal block (group relative) is within the file's + * own block reservation window range. + * + * If the reservation window is outside the goal allocation group, return 0; + * grp_goal (given goal block) could be -1, which means no specific + * goal block. In this case, always return 1. + * If the goal block is within the reservation window, return 1; + * otherwise, return 0; + */ +static int +goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal, + unsigned int group, struct super_block * sb) +{ + ext3_fsblk_t group_first_block, group_last_block; + + group_first_block = ext3_group_first_block_no(sb, group); + group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1); + + if ((rsv->_rsv_start > group_last_block) || + (rsv->_rsv_end < group_first_block)) + return 0; + if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start) + || (grp_goal + group_first_block > rsv->_rsv_end))) + return 0; + return 1; +} + +/** + * search_reserve_window() + * @rb_root: root of reservation tree + * @goal: target allocation block + * + * Find the reserved window which includes the goal, or the previous one + * if the goal is not in any window. + * Returns NULL if there are no windows or if all windows start after the goal. + */ +static struct ext3_reserve_window_node * +search_reserve_window(struct rb_root *root, ext3_fsblk_t goal) +{ + struct rb_node *n = root->rb_node; + struct ext3_reserve_window_node *rsv; + + if (!n) + return NULL; + + do { + rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node); + + if (goal < rsv->rsv_start) + n = n->rb_left; + else if (goal > rsv->rsv_end) + n = n->rb_right; + else + return rsv; + } while (n); + /* + * We've fallen off the end of the tree: the goal wasn't inside + * any particular node. OK, the previous node must be to one + * side of the interval containing the goal. If it's the RHS, + * we need to back up one. + */ + if (rsv->rsv_start > goal) { + n = rb_prev(&rsv->rsv_node); + rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node); + } + return rsv; +} + +/** + * ext3_rsv_window_add() -- Insert a window to the block reservation rb tree. + * @sb: super block + * @rsv: reservation window to add + * + * Must be called with rsv_lock hold. + */ +void ext3_rsv_window_add(struct super_block *sb, + struct ext3_reserve_window_node *rsv) +{ + struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root; + struct rb_node *node = &rsv->rsv_node; + ext3_fsblk_t start = rsv->rsv_start; + + struct rb_node ** p = &root->rb_node; + struct rb_node * parent = NULL; + struct ext3_reserve_window_node *this; + + while (*p) + { + parent = *p; + this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node); + + if (start < this->rsv_start) + p = &(*p)->rb_left; + else if (start > this->rsv_end) + p = &(*p)->rb_right; + else { + rsv_window_dump(root, 1); + BUG(); + } + } + + rb_link_node(node, parent, p); + rb_insert_color(node, root); +} + +/** + * ext3_rsv_window_remove() -- unlink a window from the reservation rb tree + * @sb: super block + * @rsv: reservation window to remove + * + * Mark the block reservation window as not allocated, and unlink it + * from the filesystem reservation window rb tree. Must be called with + * rsv_lock hold. + */ +static void rsv_window_remove(struct super_block *sb, + struct ext3_reserve_window_node *rsv) +{ + rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; + rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; + rsv->rsv_alloc_hit = 0; + rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root); +} + +/* + * rsv_is_empty() -- Check if the reservation window is allocated. + * @rsv: given reservation window to check + * + * returns 1 if the end block is EXT3_RESERVE_WINDOW_NOT_ALLOCATED. + */ +static inline int rsv_is_empty(struct ext3_reserve_window *rsv) +{ + /* a valid reservation end block could not be 0 */ + return rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED; +} + +/** + * ext3_init_block_alloc_info() + * @inode: file inode structure + * + * Allocate and initialize the reservation window structure, and + * link the window to the ext3 inode structure at last + * + * The reservation window structure is only dynamically allocated + * and linked to ext3 inode the first time the open file + * needs a new block. So, before every ext3_new_block(s) call, for + * regular files, we should check whether the reservation window + * structure exists or not. In the latter case, this function is called. + * Fail to do so will result in block reservation being turned off for that + * open file. + * + * This function is called from ext3_get_blocks_handle(), also called + * when setting the reservation window size through ioctl before the file + * is open for write (needs block allocation). + * + * Needs truncate_mutex protection prior to call this function. + */ +void ext3_init_block_alloc_info(struct inode *inode) +{ + struct ext3_inode_info *ei = EXT3_I(inode); + struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info; + struct super_block *sb = inode->i_sb; + + block_i = kmalloc(sizeof(*block_i), GFP_NOFS); + if (block_i) { + struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node; + + rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; + rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED; + + /* + * if filesystem is mounted with NORESERVATION, the goal + * reservation window size is set to zero to indicate + * block reservation is off + */ + if (!test_opt(sb, RESERVATION)) + rsv->rsv_goal_size = 0; + else + rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS; + rsv->rsv_alloc_hit = 0; + block_i->last_alloc_logical_block = 0; + block_i->last_alloc_physical_block = 0; + } + ei->i_block_alloc_info = block_i; +} + +/** + * ext3_discard_reservation() + * @inode: inode + * + * Discard(free) block reservation window on last file close, or truncate + * or at last iput(). + * + * It is being called in three cases: + * ext3_release_file(): last writer close the file + * ext3_clear_inode(): last iput(), when nobody link to this file. + * ext3_truncate(): when the block indirect map is about to change. + * + */ +void ext3_discard_reservation(struct inode *inode) +{ + struct ext3_inode_info *ei = EXT3_I(inode); + struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info; + struct ext3_reserve_window_node *rsv; + spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock; + + if (!block_i) + return; + + rsv = &block_i->rsv_window_node; + if (!rsv_is_empty(&rsv->rsv_window)) { + spin_lock(rsv_lock); + if (!rsv_is_empty(&rsv->rsv_window)) + rsv_window_remove(inode->i_sb, rsv); + spin_unlock(rsv_lock); + } +} + +/** + * ext3_free_blocks_sb() -- Free given blocks and update quota + * @handle: handle to this transaction + * @sb: super block + * @block: start physcial block to free + * @count: number of blocks to free + * @pdquot_freed_blocks: pointer to quota + */ +void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb, + ext3_fsblk_t block, unsigned long count, + unsigned long *pdquot_freed_blocks) +{ + struct buffer_head *bitmap_bh = NULL; + struct buffer_head *gd_bh; + unsigned long block_group; + ext3_grpblk_t bit; + unsigned long i; + unsigned long overflow; + struct ext3_group_desc * desc; + struct ext3_super_block * es; + struct ext3_sb_info *sbi; + int err = 0, ret; + ext3_grpblk_t group_freed; + + *pdquot_freed_blocks = 0; + sbi = EXT3_SB(sb); + es = sbi->s_es; + if (block < le32_to_cpu(es->s_first_data_block) || + block + count < block || + block + count > le32_to_cpu(es->s_blocks_count)) { + ext3_error (sb, "ext3_free_blocks", + "Freeing blocks not in datazone - " + "block = "E3FSBLK", count = %lu", block, count); + goto error_return; + } + + ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1); + +do_more: + overflow = 0; + block_group = (block - le32_to_cpu(es->s_first_data_block)) / + EXT3_BLOCKS_PER_GROUP(sb); + bit = (block - le32_to_cpu(es->s_first_data_block)) % + EXT3_BLOCKS_PER_GROUP(sb); + /* + * Check to see if we are freeing blocks across a group + * boundary. + */ + if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) { + overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb); + count -= overflow; + } + brelse(bitmap_bh); + bitmap_bh = read_block_bitmap(sb, block_group); + if (!bitmap_bh) + goto error_return; + desc = ext3_get_group_desc (sb, block_group, &gd_bh); + if (!desc) + goto error_return; + + if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) || + in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) || + in_range (block, le32_to_cpu(desc->bg_inode_table), + sbi->s_itb_per_group) || + in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table), + sbi->s_itb_per_group)) + ext3_error (sb, "ext3_free_blocks", + "Freeing blocks in system zones - " + "Block = "E3FSBLK", count = %lu", + block, count); + + /* + * We are about to start releasing blocks in the bitmap, + * so we need undo access. + */ + /* @@@ check errors */ + BUFFER_TRACE(bitmap_bh, "getting undo access"); + err = ext3_journal_get_undo_access(handle, bitmap_bh); + if (err) + goto error_return; + + /* + * We are about to modify some metadata. Call the journal APIs + * to unshare ->b_data if a currently-committing transaction is + * using it + */ + BUFFER_TRACE(gd_bh, "get_write_access"); + err = ext3_journal_get_write_access(handle, gd_bh); + if (err) + goto error_return; + + jbd_lock_bh_state(bitmap_bh); + + for (i = 0, group_freed = 0; i < count; i++) { + /* + * An HJ special. This is expensive... + */ +#ifdef CONFIG_JBD_DEBUG + jbd_unlock_bh_state(bitmap_bh); + { + struct buffer_head *debug_bh; + debug_bh = sb_find_get_block(sb, block + i); + if (debug_bh) { + BUFFER_TRACE(debug_bh, "Deleted!"); + if (!bh2jh(bitmap_bh)->b_committed_data) + BUFFER_TRACE(debug_bh, + "No commited data in bitmap"); + BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap"); + __brelse(debug_bh); + } + } + jbd_lock_bh_state(bitmap_bh); +#endif + if (need_resched()) { + jbd_unlock_bh_state(bitmap_bh); + cond_resched(); + jbd_lock_bh_state(bitmap_bh); + } + /* @@@ This prevents newly-allocated data from being + * freed and then reallocated within the same + * transaction. + * + * Ideally we would want to allow that to happen, but to + * do so requires making journal_forget() capable of + * revoking the queued write of a data block, which + * implies blocking on the journal lock. *forget() + * cannot block due to truncate races. + * + * Eventually we can fix this by making journal_forget() + * return a status indicating whether or not it was able + * to revoke the buffer. On successful revoke, it is + * safe not to set the allocation bit in the committed + * bitmap, because we know that there is no outstanding + * activity on the buffer any more and so it is safe to + * reallocate it. + */ + BUFFER_TRACE(bitmap_bh, "set in b_committed_data"); + J_ASSERT_BH(bitmap_bh, + bh2jh(bitmap_bh)->b_committed_data != NULL); + ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i, + bh2jh(bitmap_bh)->b_committed_data); + + /* + * We clear the bit in the bitmap after setting the committed + * data bit, because this is the reverse order to that which + * the allocator uses. + */ + BUFFER_TRACE(bitmap_bh, "clear bit"); + if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group), + bit + i, bitmap_bh->b_data)) { + jbd_unlock_bh_state(bitmap_bh); + ext3_error(sb, __FUNCTION__, + "bit already cleared for block "E3FSBLK, + block + i); + jbd_lock_bh_state(bitmap_bh); + BUFFER_TRACE(bitmap_bh, "bit already cleared"); + } else { + group_freed++; + } + } + jbd_unlock_bh_state(bitmap_bh); + + spin_lock(sb_bgl_lock(sbi, block_group)); + desc->bg_free_blocks_count = + cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) + + group_freed); + spin_unlock(sb_bgl_lock(sbi, block_group)); + percpu_counter_mod(&sbi->s_freeblocks_counter, count); + + /* We dirtied the bitmap block */ + BUFFER_TRACE(bitmap_bh, "dirtied bitmap block"); + err = ext3_journal_dirty_metadata(handle, bitmap_bh); + + /* And the group descriptor block */ + BUFFER_TRACE(gd_bh, "dirtied group descriptor block"); + ret = ext3_journal_dirty_metadata(handle, gd_bh); + if (!err) err = ret; + *pdquot_freed_blocks += group_freed; + + if (overflow && !err) { + block += count; + count = overflow; + goto do_more; + } + sb->s_dirt = 1; +error_return: + brelse(bitmap_bh); + ext3_std_error(sb, err); + return; +} + +/** + * ext3_free_blocks() -- Free given blocks and update quota + * @handle: handle for this transaction + * @inode: inode + * @block: start physical block to free + * @count: number of blocks to count + */ +void ext3_free_blocks(handle_t *handle, struct inode *inode, + ext3_fsblk_t block, unsigned long count) +{ + struct super_block * sb; + unsigned long dquot_freed_blocks; + + sb = inode->i_sb; + if (!sb) { + printk ("ext3_free_blocks: nonexistent device"); + return; + } + ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks); + if (dquot_freed_blocks) + DQUOT_FREE_BLOCK(inode, dquot_freed_blocks); + return; +} + +/** + * ext3_test_allocatable() + * @nr: given allocation block group + * @bh: bufferhead contains the bitmap of the given block group + * + * For ext3 allocations, we must not reuse any blocks which are + * allocated in the bitmap buffer's "last committed data" copy. This + * prevents deletes from freeing up the page for reuse until we have + * committed the delete transaction. + * + * If we didn't do this, then deleting something and reallocating it as + * data would allow the old block to be overwritten before the + * transaction committed (because we force data to disk before commit). + * This would lead to corruption if we crashed between overwriting the + * data and committing the delete. + * + * @@@ We may want to make this allocation behaviour conditional on + * data-writes at some point, and disable it for metadata allocations or + * sync-data inodes. + */ +static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh) +{ + int ret; + struct journal_head *jh = bh2jh(bh); + + if (ext3_test_bit(nr, bh->b_data)) + return 0; + + jbd_lock_bh_state(bh); + if (!jh->b_committed_data) + ret = 1; + else + ret = !ext3_test_bit(nr, jh->b_committed_data); + jbd_unlock_bh_state(bh); + return ret; +} + +/** + * bitmap_search_next_usable_block() + * @start: the starting block (group relative) of the search + * @bh: bufferhead contains the block group bitmap + * @maxblocks: the ending block (group relative) of the reservation + * + * The bitmap search --- search forward alternately through the actual + * bitmap on disk and the last-committed copy in journal, until we find a + * bit free in both bitmaps. + */ +static ext3_grpblk_t +bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh, + ext3_grpblk_t maxblocks) +{ + ext3_grpblk_t next; + struct journal_head *jh = bh2jh(bh); + + while (start < maxblocks) { + next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start); + if (next >= maxblocks) + return -1; + if (ext3_test_allocatable(next, bh)) + return next; + jbd_lock_bh_state(bh); + if (jh->b_committed_data) + start = ext3_find_next_zero_bit(jh->b_committed_data, + maxblocks, next); + jbd_unlock_bh_state(bh); + } + return -1; +} + +/** + * find_next_usable_block() + * @start: the starting block (group relative) to find next + * allocatable block in bitmap. + * @bh: bufferhead contains the block group bitmap + * @maxblocks: the ending block (group relative) for the search + * + * Find an allocatable block in a bitmap. We honor both the bitmap and + * its last-committed copy (if that exists), and perform the "most + * appropriate allocation" algorithm of looking for a free block near + * the initial goal; then for a free byte somewhere in the bitmap; then + * for any free bit in the bitmap. + */ +static ext3_grpblk_t +find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh, + ext3_grpblk_t maxblocks) +{ + ext3_grpblk_t here, next; + char *p, *r; + + if (start > 0) { + /* + * The goal was occupied; search forward for a free + * block within the next XX blocks. + * + * end_goal is more or less random, but it has to be + * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the + * next 64-bit boundary is simple.. + */ + ext3_grpblk_t end_goal = (start + 63) & ~63; + if (end_goal > maxblocks) + end_goal = maxblocks; + here = ext3_find_next_zero_bit(bh->b_data, end_goal, start); + if (here < end_goal && ext3_test_allocatable(here, bh)) + return here; + ext3_debug("Bit not found near goal\n"); + } + + here = start; + if (here < 0) + here = 0; + + p = ((char *)bh->b_data) + (here >> 3); + r = memscan(p, 0, (maxblocks - here + 7) >> 3); + next = (r - ((char *)bh->b_data)) << 3; + + if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh)) + return next; + + /* + * The bitmap search --- search forward alternately through the actual + * bitmap and the last-committed copy until we find a bit free in + * both + */ + here = bitmap_search_next_usable_block(here, bh, maxblocks); + return here; +} + +/** + * claim_block() + * @block: the free block (group relative) to allocate + * @bh: the bufferhead containts the block group bitmap + * + * We think we can allocate this block in this bitmap. Try to set the bit. + * If that succeeds then check that nobody has allocated and then freed the + * block since we saw that is was not marked in b_committed_data. If it _was_ + * allocated and freed then clear the bit in the bitmap again and return + * zero (failure). + */ +static inline int +claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh) +{ + struct journal_head *jh = bh2jh(bh); + int ret; + + if (ext3_set_bit_atomic(lock, block, bh->b_data)) + return 0; + jbd_lock_bh_state(bh); + if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) { + ext3_clear_bit_atomic(lock, block, bh->b_data); + ret = 0; + } else { + ret = 1; + } + jbd_unlock_bh_state(bh); + return ret; +} + +/** + * ext3_try_to_allocate() + * @sb: superblock + * @handle: handle to this transaction + * @group: given allocation block group + * @bitmap_bh: bufferhead holds the block bitmap + * @grp_goal: given target block within the group + * @count: target number of blocks to allocate + * @my_rsv: reservation window + * + * Attempt to allocate blocks within a give range. Set the range of allocation + * first, then find the first free bit(s) from the bitmap (within the range), + * and at last, allocate the blocks by claiming the found free bit as allocated. + * + * To set the range of this allocation: + * if there is a reservation window, only try to allocate block(s) from the + * file's own reservation window; + * Otherwise, the allocation range starts from the give goal block, ends at + * the block group's last block. + * + * If we failed to allocate the desired block then we may end up crossing to a + * new bitmap. In that case we must release write access to the old one via + * ext3_journal_release_buffer(), else we'll run out of credits. + */ +static ext3_grpblk_t +ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group, + struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal, + unsigned long *count, struct ext3_reserve_window *my_rsv) +{ + ext3_fsblk_t group_first_block; + ext3_grpblk_t start, end; + unsigned long num = 0; + + /* we do allocation within the reservation window if we have a window */ + if (my_rsv) { + group_first_block = ext3_group_first_block_no(sb, group); + if (my_rsv->_rsv_start >= group_first_block) + start = my_rsv->_rsv_start - group_first_block; + else + /* reservation window cross group boundary */ + start = 0; + end = my_rsv->_rsv_end - group_first_block + 1; + if (end > EXT3_BLOCKS_PER_GROUP(sb)) + /* reservation window crosses group boundary */ + end = EXT3_BLOCKS_PER_GROUP(sb); + if ((start <= grp_goal) && (grp_goal < end)) + start = grp_goal; + else + grp_goal = -1; + } else { + if (grp_goal > 0) + start = grp_goal; + else + start = 0; + end = EXT3_BLOCKS_PER_GROUP(sb); + } + + BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb)); + +repeat: + if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) { + grp_goal = find_next_usable_block(start, bitmap_bh, end); + if (grp_goal < 0) + goto fail_access; + if (!my_rsv) { + int i; + + for (i = 0; i < 7 && grp_goal > start && + ext3_test_allocatable(grp_goal - 1, + bitmap_bh); + i++, grp_goal--) + ; + } + } + start = grp_goal; + + if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), + grp_goal, bitmap_bh)) { + /* + * The block was allocated by another thread, or it was + * allocated and then freed by another thread + */ + start++; + grp_goal++; + if (start >= end) + goto fail_access; + goto repeat; + } + num++; + grp_goal++; + while (num < *count && grp_goal < end + && ext3_test_allocatable(grp_goal, bitmap_bh) + && claim_block(sb_bgl_lock(EXT3_SB(sb), group), + grp_goal, bitmap_bh)) { + num++; + grp_goal++; + } + *count = num; + return grp_goal - num; +fail_access: + *count = num; + return -1; +} + +/** + * find_next_reservable_window(): + * find a reservable space within the given range. + * It does not allocate the reservation window for now: + * alloc_new_reservation() will do the work later. + * + * @search_head: the head of the searching list; + * This is not necessarily the list head of the whole filesystem + * + * We have both head and start_block to assist the search + * for the reservable space. The list starts from head, + * but we will shift to the place where start_block is, + * then start from there, when looking for a reservable space. + * + * @size: the target new reservation window size + * + * @group_first_block: the first block we consider to start + * the real search from + * + * @last_block: + * the maximum block number that our goal reservable space + * could start from. This is normally the last block in this + * group. The search will end when we found the start of next + * possible reservable space is out of this boundary. + * This could handle the cross boundary reservation window + * request. + * + * basically we search from the given range, rather than the whole + * reservation double linked list, (start_block, last_block) + * to find a free region that is of my size and has not + * been reserved. + * + */ +static int find_next_reservable_window( + struct ext3_reserve_window_node *search_head, + struct ext3_reserve_window_node *my_rsv, + struct super_block * sb, + ext3_fsblk_t start_block, + ext3_fsblk_t last_block) +{ + struct rb_node *next; + struct ext3_reserve_window_node *rsv, *prev; + ext3_fsblk_t cur; + int size = my_rsv->rsv_goal_size; + + /* TODO: make the start of the reservation window byte-aligned */ + /* cur = *start_block & ~7;*/ + cur = start_block; + rsv = search_head; + if (!rsv) + return -1; + + while (1) { + if (cur <= rsv->rsv_end) + cur = rsv->rsv_end + 1; + + /* TODO? + * in the case we could not find a reservable space + * that is what is expected, during the re-search, we could + * remember what's the largest reservable space we could have + * and return that one. + * + * For now it will fail if we could not find the reservable + * space with expected-size (or more)... + */ + if (cur > last_block) + return -1; /* fail */ + + prev = rsv; + next = rb_next(&rsv->rsv_node); + rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node); + + /* + * Reached the last reservation, we can just append to the + * previous one. + */ + if (!next) + break; + + if (cur + size <= rsv->rsv_start) { + /* + * Found a reserveable space big enough. We could + * have a reservation across the group boundary here + */ + break; + } + } + /* + * we come here either : + * when we reach the end of the whole list, + * and there is empty reservable space after last entry in the list. + * append it to the end of the list. + * + * or we found one reservable space in the middle of the list, + * return the reservation window that we could append to. + * succeed. + */ + + if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window))) + rsv_window_remove(sb, my_rsv); + + /* + * Let's book the whole avaliable window for now. We will check the + * disk bitmap later and then, if there are free blocks then we adjust + * the window size if it's larger than requested. + * Otherwise, we will remove this node from the tree next time + * call find_next_reservable_window. + */ + my_rsv->rsv_start = cur; + my_rsv->rsv_end = cur + size - 1; + my_rsv->rsv_alloc_hit = 0; + + if (prev != my_rsv) + ext3_rsv_window_add(sb, my_rsv); + + return 0; +} + +/** + * alloc_new_reservation()--allocate a new reservation window + * + * To make a new reservation, we search part of the filesystem + * reservation list (the list that inside the group). We try to + * allocate a new reservation window near the allocation goal, + * or the beginning of the group, if there is no goal. + * + * We first find a reservable space after the goal, then from + * there, we check the bitmap for the first free block after + * it. If there is no free block until the end of group, then the + * whole group is full, we failed. Otherwise, check if the free + * block is inside the expected reservable space, if so, we + * succeed. + * If the first free block is outside the reservable space, then + * start from the first free block, we search for next available + * space, and go on. + * + * on succeed, a new reservation will be found and inserted into the list + * It contains at least one free block, and it does not overlap with other + * reservation windows. + * + * failed: we failed to find a reservation window in this group + * + * @rsv: the reservation + * + * @grp_goal: The goal (group-relative). It is where the search for a + * free reservable space should start from. + * if we have a grp_goal(grp_goal >0 ), then start from there, + * no grp_goal(grp_goal = -1), we start from the first block + * of the group. + * + * @sb: the super block + * @group: the group we are trying to allocate in + * @bitmap_bh: the block group block bitmap + * + */ +static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv, + ext3_grpblk_t grp_goal, struct super_block *sb, + unsigned int group, struct buffer_head *bitmap_bh) +{ + struct ext3_reserve_window_node *search_head; + ext3_fsblk_t group_first_block, group_end_block, start_block; + ext3_grpblk_t first_free_block; + struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root; + unsigned long size; + int ret; + spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock; + + group_first_block = ext3_group_first_block_no(sb, group); + group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1); + + if (grp_goal < 0) + start_block = group_first_block; + else + start_block = grp_goal + group_first_block; + + size = my_rsv->rsv_goal_size; + + if (!rsv_is_empty(&my_rsv->rsv_window)) { + /* + * if the old reservation is cross group boundary + * and if the goal is inside the old reservation window, + * we will come here when we just failed to allocate from + * the first part of the window. We still have another part + * that belongs to the next group. In this case, there is no + * point to discard our window and try to allocate a new one + * in this group(which will fail). we should + * keep the reservation window, just simply move on. + * + * Maybe we could shift the start block of the reservation + * w |