/fs/ext3/inode.c
C | 1638 lines | 888 code | 149 blank | 601 comment | 193 complexity | fe16179b3922034779bf4ae729b816f8 MD5 | raw file
- /*
- * linux/fs/ext3/inode.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)
- *
- * from
- *
- * linux/fs/minix/inode.c
- *
- * Copyright (C) 1991, 1992 Linus Torvalds
- *
- * Goal-directed block allocation by Stephen Tweedie
- * (sct@redhat.com), 1993, 1998
- * Big-endian to little-endian byte-swapping/bitmaps by
- * David S. Miller (davem@caip.rutgers.edu), 1995
- * 64-bit file support on 64-bit platforms by Jakub Jelinek
- * (jj@sunsite.ms.mff.cuni.cz)
- *
- * Assorted race fixes, rewrite of ext3_get_block() by Al Viro, 2000
- */
- #include <linux/module.h>
- #include <linux/fs.h>
- #include <linux/time.h>
- #include <linux/ext3_jbd.h>
- #include <linux/jbd.h>
- #include <linux/highuid.h>
- #include <linux/pagemap.h>
- #include <linux/quotaops.h>
- #include <linux/string.h>
- #include <linux/buffer_head.h>
- #include <linux/writeback.h>
- #include <linux/mpage.h>
- #include <linux/uio.h>
- #include <linux/bio.h>
- #include <linux/fiemap.h>
- #include <linux/namei.h>
- #include <trace/events/ext3.h>
- #include "xattr.h"
- #include "acl.h"
- static int ext3_writepage_trans_blocks(struct inode *inode);
- static int ext3_block_truncate_page(struct inode *inode, loff_t from);
- /*
- * Test whether an inode is a fast symlink.
- */
- static int ext3_inode_is_fast_symlink(struct inode *inode)
- {
- int ea_blocks = EXT3_I(inode)->i_file_acl ?
- (inode->i_sb->s_blocksize >> 9) : 0;
- return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
- }
- /*
- * The ext3 forget function must perform a revoke if we are freeing data
- * which has been journaled. Metadata (eg. indirect blocks) must be
- * revoked in all cases.
- *
- * "bh" may be NULL: a metadata block may have been freed from memory
- * but there may still be a record of it in the journal, and that record
- * still needs to be revoked.
- */
- int ext3_forget(handle_t *handle, int is_metadata, struct inode *inode,
- struct buffer_head *bh, ext3_fsblk_t blocknr)
- {
- int err;
- might_sleep();
- trace_ext3_forget(inode, is_metadata, blocknr);
- BUFFER_TRACE(bh, "enter");
- jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
- "data mode %lx\n",
- bh, is_metadata, inode->i_mode,
- test_opt(inode->i_sb, DATA_FLAGS));
- /* Never use the revoke function if we are doing full data
- * journaling: there is no need to, and a V1 superblock won't
- * support it. Otherwise, only skip the revoke on un-journaled
- * data blocks. */
- if (test_opt(inode->i_sb, DATA_FLAGS) == EXT3_MOUNT_JOURNAL_DATA ||
- (!is_metadata && !ext3_should_journal_data(inode))) {
- if (bh) {
- BUFFER_TRACE(bh, "call journal_forget");
- return ext3_journal_forget(handle, bh);
- }
- return 0;
- }
- /*
- * data!=journal && (is_metadata || should_journal_data(inode))
- */
- BUFFER_TRACE(bh, "call ext3_journal_revoke");
- err = ext3_journal_revoke(handle, blocknr, bh);
- if (err)
- ext3_abort(inode->i_sb, __func__,
- "error %d when attempting revoke", err);
- BUFFER_TRACE(bh, "exit");
- return err;
- }
- /*
- * Work out how many blocks we need to proceed with the next chunk of a
- * truncate transaction.
- */
- static unsigned long blocks_for_truncate(struct inode *inode)
- {
- unsigned long needed;
- needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
- /* Give ourselves just enough room to cope with inodes in which
- * i_blocks is corrupt: we've seen disk corruptions in the past
- * which resulted in random data in an inode which looked enough
- * like a regular file for ext3 to try to delete it. Things
- * will go a bit crazy if that happens, but at least we should
- * try not to panic the whole kernel. */
- if (needed < 2)
- needed = 2;
- /* But we need to bound the transaction so we don't overflow the
- * journal. */
- if (needed > EXT3_MAX_TRANS_DATA)
- needed = EXT3_MAX_TRANS_DATA;
- return EXT3_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
- }
- /*
- * Truncate transactions can be complex and absolutely huge. So we need to
- * be able to restart the transaction at a conventient checkpoint to make
- * sure we don't overflow the journal.
- *
- * start_transaction gets us a new handle for a truncate transaction,
- * and extend_transaction tries to extend the existing one a bit. If
- * extend fails, we need to propagate the failure up and restart the
- * transaction in the top-level truncate loop. --sct
- */
- static handle_t *start_transaction(struct inode *inode)
- {
- handle_t *result;
- result = ext3_journal_start(inode, blocks_for_truncate(inode));
- if (!IS_ERR(result))
- return result;
- ext3_std_error(inode->i_sb, PTR_ERR(result));
- return result;
- }
- /*
- * Try to extend this transaction for the purposes of truncation.
- *
- * Returns 0 if we managed to create more room. If we can't create more
- * room, and the transaction must be restarted we return 1.
- */
- static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
- {
- if (handle->h_buffer_credits > EXT3_RESERVE_TRANS_BLOCKS)
- return 0;
- if (!ext3_journal_extend(handle, blocks_for_truncate(inode)))
- return 0;
- return 1;
- }
- /*
- * Restart the transaction associated with *handle. This does a commit,
- * so before we call here everything must be consistently dirtied against
- * this transaction.
- */
- static int truncate_restart_transaction(handle_t *handle, struct inode *inode)
- {
- int ret;
- jbd_debug(2, "restarting handle %p\n", handle);
- /*
- * Drop truncate_mutex to avoid deadlock with ext3_get_blocks_handle
- * At this moment, get_block can be called only for blocks inside
- * i_size since page cache has been already dropped and writes are
- * blocked by i_mutex. So we can safely drop the truncate_mutex.
- */
- mutex_unlock(&EXT3_I(inode)->truncate_mutex);
- ret = ext3_journal_restart(handle, blocks_for_truncate(inode));
- mutex_lock(&EXT3_I(inode)->truncate_mutex);
- return ret;
- }
- /*
- * Called at inode eviction from icache
- */
- void ext3_evict_inode (struct inode *inode)
- {
- struct ext3_inode_info *ei = EXT3_I(inode);
- struct ext3_block_alloc_info *rsv;
- handle_t *handle;
- int want_delete = 0;
- trace_ext3_evict_inode(inode);
- if (!inode->i_nlink && !is_bad_inode(inode)) {
- dquot_initialize(inode);
- want_delete = 1;
- }
- /*
- * When journalling data dirty buffers are tracked only in the journal.
- * So although mm thinks everything is clean and ready for reaping the
- * inode might still have some pages to write in the running
- * transaction or waiting to be checkpointed. Thus calling
- * journal_invalidatepage() (via truncate_inode_pages()) to discard
- * these buffers can cause data loss. Also even if we did not discard
- * these buffers, we would have no way to find them after the inode
- * is reaped and thus user could see stale data if he tries to read
- * them before the transaction is checkpointed. So be careful and
- * force everything to disk here... We use ei->i_datasync_tid to
- * store the newest transaction containing inode's data.
- *
- * Note that directories do not have this problem because they don't
- * use page cache.
- */
- if (inode->i_nlink && ext3_should_journal_data(inode) &&
- (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
- tid_t commit_tid = atomic_read(&ei->i_datasync_tid);
- journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
- log_start_commit(journal, commit_tid);
- log_wait_commit(journal, commit_tid);
- filemap_write_and_wait(&inode->i_data);
- }
- truncate_inode_pages(&inode->i_data, 0);
- ext3_discard_reservation(inode);
- rsv = ei->i_block_alloc_info;
- ei->i_block_alloc_info = NULL;
- if (unlikely(rsv))
- kfree(rsv);
- if (!want_delete)
- goto no_delete;
- handle = start_transaction(inode);
- if (IS_ERR(handle)) {
- /*
- * If we're going to skip the normal cleanup, we still need to
- * make sure that the in-core orphan linked list is properly
- * cleaned up.
- */
- ext3_orphan_del(NULL, inode);
- goto no_delete;
- }
- if (IS_SYNC(inode))
- handle->h_sync = 1;
- inode->i_size = 0;
- if (inode->i_blocks)
- ext3_truncate(inode);
- /*
- * Kill off the orphan record created when the inode lost the last
- * link. Note that ext3_orphan_del() has to be able to cope with the
- * deletion of a non-existent orphan - ext3_truncate() could
- * have removed the record.
- */
- ext3_orphan_del(handle, inode);
- ei->i_dtime = get_seconds();
- /*
- * One subtle ordering requirement: if anything has gone wrong
- * (transaction abort, IO errors, whatever), then we can still
- * do these next steps (the fs will already have been marked as
- * having errors), but we can't free the inode if the mark_dirty
- * fails.
- */
- if (ext3_mark_inode_dirty(handle, inode)) {
- /* If that failed, just dquot_drop() and be done with that */
- dquot_drop(inode);
- end_writeback(inode);
- } else {
- ext3_xattr_delete_inode(handle, inode);
- dquot_free_inode(inode);
- dquot_drop(inode);
- end_writeback(inode);
- ext3_free_inode(handle, inode);
- }
- ext3_journal_stop(handle);
- return;
- no_delete:
- end_writeback(inode);
- dquot_drop(inode);
- }
- typedef struct {
- __le32 *p;
- __le32 key;
- struct buffer_head *bh;
- } Indirect;
- static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
- {
- p->key = *(p->p = v);
- p->bh = bh;
- }
- static int verify_chain(Indirect *from, Indirect *to)
- {
- while (from <= to && from->key == *from->p)
- from++;
- return (from > to);
- }
- /**
- * ext3_block_to_path - parse the block number into array of offsets
- * @inode: inode in question (we are only interested in its superblock)
- * @i_block: block number to be parsed
- * @offsets: array to store the offsets in
- * @boundary: set this non-zero if the referred-to block is likely to be
- * followed (on disk) by an indirect block.
- *
- * To store the locations of file's data ext3 uses a data structure common
- * for UNIX filesystems - tree of pointers anchored in the inode, with
- * data blocks at leaves and indirect blocks in intermediate nodes.
- * This function translates the block number into path in that tree -
- * return value is the path length and @offsets[n] is the offset of
- * pointer to (n+1)th node in the nth one. If @block is out of range
- * (negative or too large) warning is printed and zero returned.
- *
- * Note: function doesn't find node addresses, so no IO is needed. All
- * we need to know is the capacity of indirect blocks (taken from the
- * inode->i_sb).
- */
- /*
- * Portability note: the last comparison (check that we fit into triple
- * indirect block) is spelled differently, because otherwise on an
- * architecture with 32-bit longs and 8Kb pages we might get into trouble
- * if our filesystem had 8Kb blocks. We might use long long, but that would
- * kill us on x86. Oh, well, at least the sign propagation does not matter -
- * i_block would have to be negative in the very beginning, so we would not
- * get there at all.
- */
- static int ext3_block_to_path(struct inode *inode,
- long i_block, int offsets[4], int *boundary)
- {
- int ptrs = EXT3_ADDR_PER_BLOCK(inode->i_sb);
- int ptrs_bits = EXT3_ADDR_PER_BLOCK_BITS(inode->i_sb);
- const long direct_blocks = EXT3_NDIR_BLOCKS,
- indirect_blocks = ptrs,
- double_blocks = (1 << (ptrs_bits * 2));
- int n = 0;
- int final = 0;
- if (i_block < 0) {
- ext3_warning (inode->i_sb, "ext3_block_to_path", "block < 0");
- } else if (i_block < direct_blocks) {
- offsets[n++] = i_block;
- final = direct_blocks;
- } else if ( (i_block -= direct_blocks) < indirect_blocks) {
- offsets[n++] = EXT3_IND_BLOCK;
- offsets[n++] = i_block;
- final = ptrs;
- } else if ((i_block -= indirect_blocks) < double_blocks) {
- offsets[n++] = EXT3_DIND_BLOCK;
- offsets[n++] = i_block >> ptrs_bits;
- offsets[n++] = i_block & (ptrs - 1);
- final = ptrs;
- } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
- offsets[n++] = EXT3_TIND_BLOCK;
- offsets[n++] = i_block >> (ptrs_bits * 2);
- offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
- offsets[n++] = i_block & (ptrs - 1);
- final = ptrs;
- } else {
- ext3_warning(inode->i_sb, "ext3_block_to_path", "block > big");
- }
- if (boundary)
- *boundary = final - 1 - (i_block & (ptrs - 1));
- return n;
- }
- /**
- * ext3_get_branch - read the chain of indirect blocks leading to data
- * @inode: inode in question
- * @depth: depth of the chain (1 - direct pointer, etc.)
- * @offsets: offsets of pointers in inode/indirect blocks
- * @chain: place to store the result
- * @err: here we store the error value
- *
- * Function fills the array of triples <key, p, bh> and returns %NULL
- * if everything went OK or the pointer to the last filled triple
- * (incomplete one) otherwise. Upon the return chain[i].key contains
- * the number of (i+1)-th block in the chain (as it is stored in memory,
- * i.e. little-endian 32-bit), chain[i].p contains the address of that
- * number (it points into struct inode for i==0 and into the bh->b_data
- * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
- * block for i>0 and NULL for i==0. In other words, it holds the block
- * numbers of the chain, addresses they were taken from (and where we can
- * verify that chain did not change) and buffer_heads hosting these
- * numbers.
- *
- * Function stops when it stumbles upon zero pointer (absent block)
- * (pointer to last triple returned, *@err == 0)
- * or when it gets an IO error reading an indirect block
- * (ditto, *@err == -EIO)
- * or when it notices that chain had been changed while it was reading
- * (ditto, *@err == -EAGAIN)
- * or when it reads all @depth-1 indirect blocks successfully and finds
- * the whole chain, all way to the data (returns %NULL, *err == 0).
- */
- static Indirect *ext3_get_branch(struct inode *inode, int depth, int *offsets,
- Indirect chain[4], int *err)
- {
- struct super_block *sb = inode->i_sb;
- Indirect *p = chain;
- struct buffer_head *bh;
- *err = 0;
- /* i_data is not going away, no lock needed */
- add_chain (chain, NULL, EXT3_I(inode)->i_data + *offsets);
- if (!p->key)
- goto no_block;
- while (--depth) {
- bh = sb_bread(sb, le32_to_cpu(p->key));
- if (!bh)
- goto failure;
- /* Reader: pointers */
- if (!verify_chain(chain, p))
- goto changed;
- add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
- /* Reader: end */
- if (!p->key)
- goto no_block;
- }
- return NULL;
- changed:
- brelse(bh);
- *err = -EAGAIN;
- goto no_block;
- failure:
- *err = -EIO;
- no_block:
- return p;
- }
- /**
- * ext3_find_near - find a place for allocation with sufficient locality
- * @inode: owner
- * @ind: descriptor of indirect block.
- *
- * This function returns the preferred place for block allocation.
- * It is used when heuristic for sequential allocation fails.
- * Rules are:
- * + if there is a block to the left of our position - allocate near it.
- * + if pointer will live in indirect block - allocate near that block.
- * + if pointer will live in inode - allocate in the same
- * cylinder group.
- *
- * In the latter case we colour the starting block by the callers PID to
- * prevent it from clashing with concurrent allocations for a different inode
- * in the same block group. The PID is used here so that functionally related
- * files will be close-by on-disk.
- *
- * Caller must make sure that @ind is valid and will stay that way.
- */
- static ext3_fsblk_t ext3_find_near(struct inode *inode, Indirect *ind)
- {
- struct ext3_inode_info *ei = EXT3_I(inode);
- __le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
- __le32 *p;
- ext3_fsblk_t bg_start;
- ext3_grpblk_t colour;
- /* Try to find previous block */
- for (p = ind->p - 1; p >= start; p--) {
- if (*p)
- return le32_to_cpu(*p);
- }
- /* No such thing, so let's try location of indirect block */
- if (ind->bh)
- return ind->bh->b_blocknr;
- /*
- * It is going to be referred to from the inode itself? OK, just put it
- * into the same cylinder group then.
- */
- bg_start = ext3_group_first_block_no(inode->i_sb, ei->i_block_group);
- colour = (current->pid % 16) *
- (EXT3_BLOCKS_PER_GROUP(inode->i_sb) / 16);
- return bg_start + colour;
- }
- /**
- * ext3_find_goal - find a preferred place for allocation.
- * @inode: owner
- * @block: block we want
- * @partial: pointer to the last triple within a chain
- *
- * Normally this function find the preferred place for block allocation,
- * returns it.
- */
- static ext3_fsblk_t ext3_find_goal(struct inode *inode, long block,
- Indirect *partial)
- {
- struct ext3_block_alloc_info *block_i;
- block_i = EXT3_I(inode)->i_block_alloc_info;
- /*
- * try the heuristic for sequential allocation,
- * failing that at least try to get decent locality.
- */
- if (block_i && (block == block_i->last_alloc_logical_block + 1)
- && (block_i->last_alloc_physical_block != 0)) {
- return block_i->last_alloc_physical_block + 1;
- }
- return ext3_find_near(inode, partial);
- }
- /**
- * ext3_blks_to_allocate - Look up the block map and count the number
- * of direct blocks need to be allocated for the given branch.
- *
- * @branch: chain of indirect blocks
- * @k: number of blocks need for indirect blocks
- * @blks: number of data blocks to be mapped.
- * @blocks_to_boundary: the offset in the indirect block
- *
- * return the total number of blocks to be allocate, including the
- * direct and indirect blocks.
- */
- static int ext3_blks_to_allocate(Indirect *branch, int k, unsigned long blks,
- int blocks_to_boundary)
- {
- unsigned long count = 0;
- /*
- * Simple case, [t,d]Indirect block(s) has not allocated yet
- * then it's clear blocks on that path have not allocated
- */
- if (k > 0) {
- /* right now we don't handle cross boundary allocation */
- if (blks < blocks_to_boundary + 1)
- count += blks;
- else
- count += blocks_to_boundary + 1;
- return count;
- }
- count++;
- while (count < blks && count <= blocks_to_boundary &&
- le32_to_cpu(*(branch[0].p + count)) == 0) {
- count++;
- }
- return count;
- }
- /**
- * ext3_alloc_blocks - multiple allocate blocks needed for a branch
- * @handle: handle for this transaction
- * @inode: owner
- * @goal: preferred place for allocation
- * @indirect_blks: the number of blocks need to allocate for indirect
- * blocks
- * @blks: number of blocks need to allocated for direct blocks
- * @new_blocks: on return it will store the new block numbers for
- * the indirect blocks(if needed) and the first direct block,
- * @err: here we store the error value
- *
- * return the number of direct blocks allocated
- */
- static int ext3_alloc_blocks(handle_t *handle, struct inode *inode,
- ext3_fsblk_t goal, int indirect_blks, int blks,
- ext3_fsblk_t new_blocks[4], int *err)
- {
- int target, i;
- unsigned long count = 0;
- int index = 0;
- ext3_fsblk_t current_block = 0;
- int ret = 0;
- /*
- * Here we try to allocate the requested multiple blocks at once,
- * on a best-effort basis.
- * To build a branch, we should allocate blocks for
- * the indirect blocks(if not allocated yet), and at least
- * the first direct block of this branch. That's the
- * minimum number of blocks need to allocate(required)
- */
- target = blks + indirect_blks;
- while (1) {
- count = target;
- /* allocating blocks for indirect blocks and direct blocks */
- current_block = ext3_new_blocks(handle,inode,goal,&count,err);
- if (*err)
- goto failed_out;
- target -= count;
- /* allocate blocks for indirect blocks */
- while (index < indirect_blks && count) {
- new_blocks[index++] = current_block++;
- count--;
- }
- if (count > 0)
- break;
- }
- /* save the new block number for the first direct block */
- new_blocks[index] = current_block;
- /* total number of blocks allocated for direct blocks */
- ret = count;
- *err = 0;
- return ret;
- failed_out:
- for (i = 0; i <index; i++)
- ext3_free_blocks(handle, inode, new_blocks[i], 1);
- return ret;
- }
- /**
- * ext3_alloc_branch - allocate and set up a chain of blocks.
- * @handle: handle for this transaction
- * @inode: owner
- * @indirect_blks: number of allocated indirect blocks
- * @blks: number of allocated direct blocks
- * @goal: preferred place for allocation
- * @offsets: offsets (in the blocks) to store the pointers to next.
- * @branch: place to store the chain in.
- *
- * This function allocates blocks, zeroes out all but the last one,
- * links them into chain and (if we are synchronous) writes them to disk.
- * In other words, it prepares a branch that can be spliced onto the
- * inode. It stores the information about that chain in the branch[], in
- * the same format as ext3_get_branch() would do. We are calling it after
- * we had read the existing part of chain and partial points to the last
- * triple of that (one with zero ->key). Upon the exit we have the same
- * picture as after the successful ext3_get_block(), except that in one
- * place chain is disconnected - *branch->p is still zero (we did not
- * set the last link), but branch->key contains the number that should
- * be placed into *branch->p to fill that gap.
- *
- * If allocation fails we free all blocks we've allocated (and forget
- * their buffer_heads) and return the error value the from failed
- * ext3_alloc_block() (normally -ENOSPC). Otherwise we set the chain
- * as described above and return 0.
- */
- static int ext3_alloc_branch(handle_t *handle, struct inode *inode,
- int indirect_blks, int *blks, ext3_fsblk_t goal,
- int *offsets, Indirect *branch)
- {
- int blocksize = inode->i_sb->s_blocksize;
- int i, n = 0;
- int err = 0;
- struct buffer_head *bh;
- int num;
- ext3_fsblk_t new_blocks[4];
- ext3_fsblk_t current_block;
- num = ext3_alloc_blocks(handle, inode, goal, indirect_blks,
- *blks, new_blocks, &err);
- if (err)
- return err;
- branch[0].key = cpu_to_le32(new_blocks[0]);
- /*
- * metadata blocks and data blocks are allocated.
- */
- for (n = 1; n <= indirect_blks; n++) {
- /*
- * Get buffer_head for parent block, zero it out
- * and set the pointer to new one, then send
- * parent to disk.
- */
- bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
- branch[n].bh = bh;
- lock_buffer(bh);
- BUFFER_TRACE(bh, "call get_create_access");
- err = ext3_journal_get_create_access(handle, bh);
- if (err) {
- unlock_buffer(bh);
- brelse(bh);
- goto failed;
- }
- memset(bh->b_data, 0, blocksize);
- branch[n].p = (__le32 *) bh->b_data + offsets[n];
- branch[n].key = cpu_to_le32(new_blocks[n]);
- *branch[n].p = branch[n].key;
- if ( n == indirect_blks) {
- current_block = new_blocks[n];
- /*
- * End of chain, update the last new metablock of
- * the chain to point to the new allocated
- * data blocks numbers
- */
- for (i=1; i < num; i++)
- *(branch[n].p + i) = cpu_to_le32(++current_block);
- }
- BUFFER_TRACE(bh, "marking uptodate");
- set_buffer_uptodate(bh);
- unlock_buffer(bh);
- BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
- err = ext3_journal_dirty_metadata(handle, bh);
- if (err)
- goto failed;
- }
- *blks = num;
- return err;
- failed:
- /* Allocation failed, free what we already allocated */
- for (i = 1; i <= n ; i++) {
- BUFFER_TRACE(branch[i].bh, "call journal_forget");
- ext3_journal_forget(handle, branch[i].bh);
- }
- for (i = 0; i <indirect_blks; i++)
- ext3_free_blocks(handle, inode, new_blocks[i], 1);
- ext3_free_blocks(handle, inode, new_blocks[i], num);
- return err;
- }
- /**
- * ext3_splice_branch - splice the allocated branch onto inode.
- * @handle: handle for this transaction
- * @inode: owner
- * @block: (logical) number of block we are adding
- * @where: location of missing link
- * @num: number of indirect blocks we are adding
- * @blks: number of direct blocks we are adding
- *
- * This function fills the missing link and does all housekeeping needed in
- * inode (->i_blocks, etc.). In case of success we end up with the full
- * chain to new block and return 0.
- */
- static int ext3_splice_branch(handle_t *handle, struct inode *inode,
- long block, Indirect *where, int num, int blks)
- {
- int i;
- int err = 0;
- struct ext3_block_alloc_info *block_i;
- ext3_fsblk_t current_block;
- struct ext3_inode_info *ei = EXT3_I(inode);
- block_i = ei->i_block_alloc_info;
- /*
- * If we're splicing into a [td]indirect block (as opposed to the
- * inode) then we need to get write access to the [td]indirect block
- * before the splice.
- */
- if (where->bh) {
- BUFFER_TRACE(where->bh, "get_write_access");
- err = ext3_journal_get_write_access(handle, where->bh);
- if (err)
- goto err_out;
- }
- /* That's it */
- *where->p = where->key;
- /*
- * Update the host buffer_head or inode to point to more just allocated
- * direct blocks blocks
- */
- if (num == 0 && blks > 1) {
- current_block = le32_to_cpu(where->key) + 1;
- for (i = 1; i < blks; i++)
- *(where->p + i ) = cpu_to_le32(current_block++);
- }
- /*
- * update the most recently allocated logical & physical block
- * in i_block_alloc_info, to assist find the proper goal block for next
- * allocation
- */
- if (block_i) {
- block_i->last_alloc_logical_block = block + blks - 1;
- block_i->last_alloc_physical_block =
- le32_to_cpu(where[num].key) + blks - 1;
- }
- /* We are done with atomic stuff, now do the rest of housekeeping */
- inode->i_ctime = CURRENT_TIME_SEC;
- ext3_mark_inode_dirty(handle, inode);
- /* ext3_mark_inode_dirty already updated i_sync_tid */
- atomic_set(&ei->i_datasync_tid, handle->h_transaction->t_tid);
- /* had we spliced it onto indirect block? */
- if (where->bh) {
- /*
- * If we spliced it onto an indirect block, we haven't
- * altered the inode. Note however that if it is being spliced
- * onto an indirect block at the very end of the file (the
- * file is growing) then we *will* alter the inode to reflect
- * the new i_size. But that is not done here - it is done in
- * generic_commit_write->__mark_inode_dirty->ext3_dirty_inode.
- */
- jbd_debug(5, "splicing indirect only\n");
- BUFFER_TRACE(where->bh, "call ext3_journal_dirty_metadata");
- err = ext3_journal_dirty_metadata(handle, where->bh);
- if (err)
- goto err_out;
- } else {
- /*
- * OK, we spliced it into the inode itself on a direct block.
- * Inode was dirtied above.
- */
- jbd_debug(5, "splicing direct\n");
- }
- return err;
- err_out:
- for (i = 1; i <= num; i++) {
- BUFFER_TRACE(where[i].bh, "call journal_forget");
- ext3_journal_forget(handle, where[i].bh);
- ext3_free_blocks(handle,inode,le32_to_cpu(where[i-1].key),1);
- }
- ext3_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks);
- return err;
- }
- /*
- * Allocation strategy is simple: if we have to allocate something, we will
- * have to go the whole way to leaf. So let's do it before attaching anything
- * to tree, set linkage between the newborn blocks, write them if sync is
- * required, recheck the path, free and repeat if check fails, otherwise
- * set the last missing link (that will protect us from any truncate-generated
- * removals - all blocks on the path are immune now) and possibly force the
- * write on the parent block.
- * That has a nice additional property: no special recovery from the failed
- * allocations is needed - we simply release blocks and do not touch anything
- * reachable from inode.
- *
- * `handle' can be NULL if create == 0.
- *
- * The BKL may not be held on entry here. Be sure to take it early.
- * return > 0, # of blocks mapped or allocated.
- * return = 0, if plain lookup failed.
- * return < 0, error case.
- */
- int ext3_get_blocks_handle(handle_t *handle, struct inode *inode,
- sector_t iblock, unsigned long maxblocks,
- struct buffer_head *bh_result,
- int create)
- {
- int err = -EIO;
- int offsets[4];
- Indirect chain[4];
- Indirect *partial;
- ext3_fsblk_t goal;
- int indirect_blks;
- int blocks_to_boundary = 0;
- int depth;
- struct ext3_inode_info *ei = EXT3_I(inode);
- int count = 0;
- ext3_fsblk_t first_block = 0;
- trace_ext3_get_blocks_enter(inode, iblock, maxblocks, create);
- J_ASSERT(handle != NULL || create == 0);
- depth = ext3_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
- if (depth == 0)
- goto out;
- partial = ext3_get_branch(inode, depth, offsets, chain, &err);
- /* Simplest case - block found, no allocation needed */
- if (!partial) {
- first_block = le32_to_cpu(chain[depth - 1].key);
- clear_buffer_new(bh_result);
- count++;
- /*map more blocks*/
- while (count < maxblocks && count <= blocks_to_boundary) {
- ext3_fsblk_t blk;
- if (!verify_chain(chain, chain + depth - 1)) {
- /*
- * Indirect block might be removed by
- * truncate while we were reading it.
- * Handling of that case: forget what we've
- * got now. Flag the err as EAGAIN, so it
- * will reread.
- */
- err = -EAGAIN;
- count = 0;
- break;
- }
- blk = le32_to_cpu(*(chain[depth-1].p + count));
- if (blk == first_block + count)
- count++;
- else
- break;
- }
- if (err != -EAGAIN)
- goto got_it;
- }
- /* Next simple case - plain lookup or failed read of indirect block */
- if (!create || err == -EIO)
- goto cleanup;
- /*
- * Block out ext3_truncate while we alter the tree
- */
- mutex_lock(&ei->truncate_mutex);
- /*
- * If the indirect block is missing while we are reading
- * the chain(ext3_get_branch() returns -EAGAIN err), or
- * if the chain has been changed after we grab the semaphore,
- * (either because another process truncated this branch, or
- * another get_block allocated this branch) re-grab the chain to see if
- * the request block has been allocated or not.
- *
- * Since we already block the truncate/other get_block
- * at this point, we will have the current copy of the chain when we
- * splice the branch into the tree.
- */
- if (err == -EAGAIN || !verify_chain(chain, partial)) {
- while (partial > chain) {
- brelse(partial->bh);
- partial--;
- }
- partial = ext3_get_branch(inode, depth, offsets, chain, &err);
- if (!partial) {
- count++;
- mutex_unlock(&ei->truncate_mutex);
- if (err)
- goto cleanup;
- clear_buffer_new(bh_result);
- goto got_it;
- }
- }
- /*
- * Okay, we need to do block allocation. Lazily initialize the block
- * allocation info here if necessary
- */
- if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
- ext3_init_block_alloc_info(inode);
- goal = ext3_find_goal(inode, iblock, partial);
- /* the number of blocks need to allocate for [d,t]indirect blocks */
- indirect_blks = (chain + depth) - partial - 1;
- /*
- * Next look up the indirect map to count the totoal number of
- * direct blocks to allocate for this branch.
- */
- count = ext3_blks_to_allocate(partial, indirect_blks,
- maxblocks, blocks_to_boundary);
- err = ext3_alloc_branch(handle, inode, indirect_blks, &count, goal,
- offsets + (partial - chain), partial);
- /*
- * The ext3_splice_branch call will free and forget any buffers
- * on the new chain if there is a failure, but that risks using
- * up transaction credits, especially for bitmaps where the
- * credits cannot be returned. Can we handle this somehow? We
- * may need to return -EAGAIN upwards in the worst case. --sct
- */
- if (!err)
- err = ext3_splice_branch(handle, inode, iblock,
- partial, indirect_blks, count);
- mutex_unlock(&ei->truncate_mutex);
- if (err)
- goto cleanup;
- set_buffer_new(bh_result);
- got_it:
- map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
- if (count > blocks_to_boundary)
- set_buffer_boundary(bh_result);
- err = count;
- /* Clean up and exit */
- partial = chain + depth - 1; /* the whole chain */
- cleanup:
- while (partial > chain) {
- BUFFER_TRACE(partial->bh, "call brelse");
- brelse(partial->bh);
- partial--;
- }
- BUFFER_TRACE(bh_result, "returned");
- out:
- trace_ext3_get_blocks_exit(inode, iblock,
- depth ? le32_to_cpu(chain[depth-1].key) : 0,
- count, err);
- return err;
- }
- /* Maximum number of blocks we map for direct IO at once. */
- #define DIO_MAX_BLOCKS 4096
- /*
- * Number of credits we need for writing DIO_MAX_BLOCKS:
- * We need sb + group descriptor + bitmap + inode -> 4
- * For B blocks with A block pointers per block we need:
- * 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
- * If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
- */
- #define DIO_CREDITS 25
- static int ext3_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
- {
- handle_t *handle = ext3_journal_current_handle();
- int ret = 0, started = 0;
- unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
- if (create && !handle) { /* Direct IO write... */
- if (max_blocks > DIO_MAX_BLOCKS)
- max_blocks = DIO_MAX_BLOCKS;
- handle = ext3_journal_start(inode, DIO_CREDITS +
- EXT3_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- goto out;
- }
- started = 1;
- }
- ret = ext3_get_blocks_handle(handle, inode, iblock,
- max_blocks, bh_result, create);
- if (ret > 0) {
- bh_result->b_size = (ret << inode->i_blkbits);
- ret = 0;
- }
- if (started)
- ext3_journal_stop(handle);
- out:
- return ret;
- }
- int ext3_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
- u64 start, u64 len)
- {
- return generic_block_fiemap(inode, fieinfo, start, len,
- ext3_get_block);
- }
- /*
- * `handle' can be NULL if create is zero
- */
- struct buffer_head *ext3_getblk(handle_t *handle, struct inode *inode,
- long block, int create, int *errp)
- {
- struct buffer_head dummy;
- int fatal = 0, err;
- J_ASSERT(handle != NULL || create == 0);
- dummy.b_state = 0;
- dummy.b_blocknr = -1000;
- buffer_trace_init(&dummy.b_history);
- err = ext3_get_blocks_handle(handle, inode, block, 1,
- &dummy, create);
- /*
- * ext3_get_blocks_handle() returns number of blocks
- * mapped. 0 in case of a HOLE.
- */
- if (err > 0) {
- if (err > 1)
- WARN_ON(1);
- err = 0;
- }
- *errp = err;
- if (!err && buffer_mapped(&dummy)) {
- struct buffer_head *bh;
- bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
- if (!bh) {
- *errp = -EIO;
- goto err;
- }
- if (buffer_new(&dummy)) {
- J_ASSERT(create != 0);
- J_ASSERT(handle != NULL);
- /*
- * Now that we do not always journal data, we should
- * keep in mind whether this should always journal the
- * new buffer as metadata. For now, regular file
- * writes use ext3_get_block instead, so it's not a
- * problem.
- */
- lock_buffer(bh);
- BUFFER_TRACE(bh, "call get_create_access");
- fatal = ext3_journal_get_create_access(handle, bh);
- if (!fatal && !buffer_uptodate(bh)) {
- memset(bh->b_data,0,inode->i_sb->s_blocksize);
- set_buffer_uptodate(bh);
- }
- unlock_buffer(bh);
- BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
- err = ext3_journal_dirty_metadata(handle, bh);
- if (!fatal)
- fatal = err;
- } else {
- BUFFER_TRACE(bh, "not a new buffer");
- }
- if (fatal) {
- *errp = fatal;
- brelse(bh);
- bh = NULL;
- }
- return bh;
- }
- err:
- return NULL;
- }
- struct buffer_head *ext3_bread(handle_t *handle, struct inode *inode,
- int block, int create, int *err)
- {
- struct buffer_head * bh;
- bh = ext3_getblk(handle, inode, block, create, err);
- if (!bh)
- return bh;
- if (buffer_uptodate(bh))
- return bh;
- ll_rw_block(READ_META, 1, &bh);
- wait_on_buffer(bh);
- if (buffer_uptodate(bh))
- return bh;
- put_bh(bh);
- *err = -EIO;
- return NULL;
- }
- static int walk_page_buffers( handle_t *handle,
- struct buffer_head *head,
- unsigned from,
- unsigned to,
- int *partial,
- int (*fn)( handle_t *handle,
- struct buffer_head *bh))
- {
- struct buffer_head *bh;
- unsigned block_start, block_end;
- unsigned blocksize = head->b_size;
- int err, ret = 0;
- struct buffer_head *next;
- for ( bh = head, block_start = 0;
- ret == 0 && (bh != head || !block_start);
- block_start = block_end, bh = next)
- {
- next = bh->b_this_page;
- block_end = block_start + blocksize;
- if (block_end <= from || block_start >= to) {
- if (partial && !buffer_uptodate(bh))
- *partial = 1;
- continue;
- }
- err = (*fn)(handle, bh);
- if (!ret)
- ret = err;
- }
- return ret;
- }
- /*
- * To preserve ordering, it is essential that the hole instantiation and
- * the data write be encapsulated in a single transaction. We cannot
- * close off a transaction and start a new one between the ext3_get_block()
- * and the commit_write(). So doing the journal_start at the start of
- * prepare_write() is the right place.
- *
- * Also, this function can nest inside ext3_writepage() ->
- * block_write_full_page(). In that case, we *know* that ext3_writepage()
- * has generated enough buffer credits to do the whole page. So we won't
- * block on the journal in that case, which is good, because the caller may
- * be PF_MEMALLOC.
- *
- * By accident, ext3 can be reentered when a transaction is open via
- * quota file writes. If we were to commit the transaction while thus
- * reentered, there can be a deadlock - we would be holding a quota
- * lock, and the commit would never complete if another thread had a
- * transaction open and was blocking on the quota lock - a ranking
- * violation.
- *
- * So what we do is to rely on the fact that journal_stop/journal_start
- * will _not_ run commit under these circumstances because handle->h_ref
- * is elevated. We'll still have enough credits for the tiny quotafile
- * write.
- */
- static int do_journal_get_write_access(handle_t *handle,
- struct buffer_head *bh)
- {
- int dirty = buffer_dirty(bh);
- int ret;
- if (!buffer_mapped(bh) || buffer_freed(bh))
- return 0;
- /*
- * __block_prepare_write() could have dirtied some buffers. Clean
- * the dirty bit as jbd2_journal_get_write_access() could complain
- * otherwise about fs integrity issues. Setting of the dirty bit
- * by __block_prepare_write() isn't a real problem here as we clear
- * the bit before releasing a page lock and thus writeback cannot
- * ever write the buffer.
- */
- if (dirty)
- clear_buffer_dirty(bh);
- ret = ext3_journal_get_write_access(handle, bh);
- if (!ret && dirty)
- ret = ext3_journal_dirty_metadata(handle, bh);
- return ret;
- }
- /*
- * Truncate blocks that were not used by write. We have to truncate the
- * pagecache as well so that corresponding buffers get properly unmapped.
- */
- static void ext3_truncate_failed_write(struct inode *inode)
- {
- truncate_inode_pages(inode->i_mapping, inode->i_size);
- ext3_truncate(inode);
- }
- /*
- * Truncate blocks that were not used by direct IO write. We have to zero out
- * the last file block as well because direct IO might have written to it.
- */
- static void ext3_truncate_failed_direct_write(struct inode *inode)
- {
- ext3_block_truncate_page(inode, inode->i_size);
- ext3_truncate(inode);
- }
- static int ext3_write_begin(struct file *file, struct address_space *mapping,
- loff_t pos, unsigned len, unsigned flags,
- struct page **pagep, void **fsdata)
- {
- struct inode *inode = mapping->host;
- int ret;
- handle_t *handle;
- int retries = 0;
- struct page *page;
- pgoff_t index;
- unsigned from, to;
- /* Reserve one block more for addition to orphan list in case
- * we allocate blocks but write fails for some reason */
- int needed_blocks = ext3_writepage_trans_blocks(inode) + 1;
- trace_ext3_write_begin(inode, pos, len, flags);
- index = pos >> PAGE_CACHE_SHIFT;
- from = pos & (PAGE_CACHE_SIZE - 1);
- to = from + len;
- retry:
- page = grab_cache_page_write_begin(mapping, index, flags);
- if (!page)
- return -ENOMEM;
- *pagep = page;
- handle = ext3_journal_start(inode, needed_blocks);
- if (IS_ERR(handle)) {
- unlock_page(page);
- page_cache_release(page);
- ret = PTR_ERR(handle);
- goto out;
- }
- ret = __block_write_begin(page, pos, len, ext3_get_block);
- if (ret)
- goto write_begin_failed;
- if (ext3_should_journal_data(inode)) {
- ret = walk_page_buffers(handle, page_buffers(page),
- from, to, NULL, do_journal_get_write_access);
- }
- write_begin_failed:
- if (ret) {
- /*
- * block_write_begin may have instantiated a few blocks
- * outside i_size. Trim these off again. Don't need
- * i_size_read because we hold i_mutex.
- *
- * Add inode to orphan list in case we crash before truncate
- * finishes. Do this only if ext3_can_truncate() agrees so
- * that orphan processing code is happy.
- */
- if (pos + len > inode->i_size && ext3_can_truncate(inode))
- ext3_orphan_add(handle, inode);
- ext3_journal_stop(handle);
- unlock_page(page);
- page_cache_release(page);
- if (pos + len > inode->i_size)
- ext3_truncate_failed_write(inode);
- }
- if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
- goto retry;
- out:
- return ret;
- }
- int ext3_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
- {
- int err = journal_dirty_data(handle, bh);
- if (err)
- ext3_journal_abort_handle(__func__, __func__,
- bh, handle, err);
- return err;
- }
- /* For ordered writepage and write_end functions */
- static int journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
- {
- /*
- * Write could have mapped the buffer but it didn't copy the data in
- * yet. So avoid filing such buffer into a transaction.
- */
- if (buffer_mapped(bh) && buffer_uptodate(bh))
- return ext3_journal_dirty_data(handle, bh);
- return 0;
- }
- /* For write_end() in data=journal mode */
- static int write_end_fn(handle_t *handle, struct buffer_head *bh)
- {
- if (!buffer_mapped(bh) || buffer_freed(bh))
- return 0;
- set_buffer_uptodate(bh);
- return ext3_journal_dirty_metadata(handle, bh);
- }
- /*
- * This is nasty and subtle: ext3_write_begin() could have allocated blocks
- * for the whole page but later we failed to copy the data in. Update inode
- * size according to what we managed to copy. The rest is going to be
- * truncated in write_end function.
- */
- static void update_file_sizes(struct inode *inode, loff_t pos, unsigned copied)
- {
- /* What matters to us is i_disksize. We don't write i_size anywhere */
- if (pos + copied > inode->i_size)
- i_size_write(inode, pos + copied);
- if (pos + copied > EXT3_I(inode)->i_disksize) {
- EXT3_I(inode)->i_disksize = pos + copied;
- mark_inode_dirty(inode);
- }
- }
- /*
- * We need to pick up the new inode size which generic_commit_write gave us
- * `file' can be NULL - eg, when called from page_symlink().
- *
- * ext3 never places buffers on inode->i_mapping->private_list. metadata
- * buffers are managed internally.
- */
- static int ext3_ordered_write_end(struct file *file,
- struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
- {
- handle_t *handle = ext3_journal_current_handle();
- struct inode *inode = file->f_mapping->host;
- unsigned from, to;
- int ret = 0, ret2;
- trace_ext3_ordered_write_end(inode, pos, len, copied);
- copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
- from = pos & (PAGE_CACHE_SIZE - 1);
- to = from + copied;
- ret = walk_page_buffers(handle, page_buffers(page),
- from, to, NULL, journal_dirty_data_fn);
- if (ret == 0)
- update_file_sizes(inode, pos, copied);
- /*
- * There may be allocated blocks outside of i_size because
- * we failed to copy some data. Prepare for truncate.
- */
- if (pos + len > inode->i_size && ext3_can_truncate(inode))
- ext3_orphan_add(handle, inode);
- ret2 = ext3_journal_stop(handle);
- if (!ret)
- ret = ret2;
- unlock_page(page);
- page_cache_release(page);
- if (pos + len > inode->i_size)
- ext3_truncate_failed_write(inode);
- return ret ? ret : copied;
- }
- static int ext3_writeback_write_end(struct file *file,
- struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
- {
- handle_t *handle = ext3_journal_current_handle();
- struct inode *inode = file->f_mapping->host;
- int ret;
- trace_ext3_writeback_write_end(inode, pos, len, copied);
- copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
- update_file_sizes(inode, pos, copied);
- /*
- * There may be allocated blocks outside of i_size because
- * we failed to copy some data. Prepare for truncate.
- */
- if (pos + len > inode->i_size && ext3_can_truncate(inode))
- ext3_orphan_add(handle, inode);
- ret = ext3_journal_stop(handle);
- unlock_page(page);
- page_cache_release(page);
- if (pos + len > inode->i_size)
- ext3_truncate_failed_write(inode);
- return ret ? ret : copied;
- }
- static int ext3_journalled_write_end(struct file *file,
- struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
- {
- handle_t *handle = ext3_journal_current_handle();
- struct inode *inode = mapping->host;
- struct ext3_inode_info *ei = EXT3_I(inode);
- int ret = 0, ret2;
- int partial = 0;
- unsigned from, to;
- trace_ext3_journalled_write_end(inode, pos, len, copied);
- from = pos & (PAGE_CACHE_SIZE - 1);
- to = from + len;
- if (copied < len) {
- if (!PageUptodate(page))
- copied = 0;
- page_zero_new_buffers(page, from + copied, to);
- to = from + copied;
- }
- ret = walk_page_buffers(handle, page_buffers(page), from,
- to, &partial, write_end_fn);
- if (!partial)
- SetPageUptodate(page);
- if (pos + copied > inode->i_size)
- i_size_write(inode, pos + copied);
- /*
- * There may be allocated blocks outside of i_size because
- * we failed to copy some data. Prepare for truncate.
- */
- if (pos + len > inode->i_size && ext3_can_truncate(inode))
- ext3_orphan_add(handle, inode);
- ext3_set_inode_state(inode, EXT3_STATE_JDATA);
- atomic_set(&ei->i_datasync_tid, handle->h_transaction->t_tid);
- if (inode->i_size > ei->i_disksize) {
- ei->i_disksize = inode->i_size;
- ret2 = ext3_mark_inode_dirty(handle, inode);
- if (!ret)
- ret = ret2;
- }
- ret2 = ext3_journal_stop(handle);
- if (!ret)
- ret = ret2;
- unlock_page(page);
- page_cache_release(page);
- if (pos + len > inode->i_size)
- ext3_truncate_failed_write(inode);
- return ret ? ret : copied;
- }
- /*
- * bmap() is special. It gets used by applications such as lilo and by
- * the swapper to find the on-disk block of a specific piece of data.
- *
- * Naturally, this is dangerous if the block concerned is still in the
- * journal. If somebody makes a swapfile on an ext3 data-journaling
- * filesystem and enables swap, then they may get a nasty shock when the
- * data getting swapped to that swapfile suddenly gets overwritten by
- * the original zero's written out previously to the journal and
- * awaiting writeback in the kernel's buffer cache.
- *
- * So, if we see any bmap calls here on a modified, data-journaled file,
- * take extra steps to flush any blocks which might be in the cache.
- */
- static sector_t ext3_bmap(struct address_space *mapping, sector_t block)
- {
- struct inode *inode = mapping->host;
- journal_t *journal;
- int err;
- if (ext3_test_inode_state(inode, EXT3_STATE_JDATA)) {
- /*
- * This is a REALLY heavyweight approach, but the use of
- * bmap on dirty files is expected to be extremely rare:
- * only if we run lilo or swapon on a freshly made file
- * do we expect this to happen.
- *
- * (bmap requires CAP_SYS_RAWIO so this does not
- * represent an unprivileged user DOS attack --- we'd be
- * in trouble if mortal users could trigger this path at
- * will.)
- *
- * NB. EXT3_STATE_JDATA is not set on files other than
- * regular files. If somebody wants to bmap a directory
- * or symlink and gets confused because the buffer
- * hasn't yet been flushed to disk, they deserve
- * everything they get.
- */
- ext3_clear_inode_state(inode, EXT3_STATE_JDATA);
- journal = EXT3_JOURNAL(inode);
- journal_lock_updates(journal);
- err = journal_flush(journal);
- journal_unlock_updates(journal);
- if (err)
- return 0;
- }
- return generic_block_bmap(mapping,block,ext3_get_block);
- }
- static int bget_one(handle_t *handle, struct buffer_head *bh)
- {
- get_bh(bh);
- return 0;
- }
- static int bput_one(handle_t *handle, struct buffer_head *bh)
- {
- put_bh(bh);
- return 0;
- }
- static int buffer_unmapped(handle_t *handle, struct buffer_head *bh)
- {
- return !buffer_mapped(bh);
- }
- /*
- * Note that we always start a transaction even if we're not journalling
- * data. This is to preserve ordering: any hole instantiation within
- * __block_write_full_page -> ext3_get_block() should be journalled
- * along with the data so we don't crash and then get metadata which
- * refers to old data.
- *
- * In all journalling modes block_write_full_page() will start the I/O.
- *
- * Problem:
- *
- * ext3_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
- * ext3_writepage()
- *
- * Similar for:
- *
- * ext3_file_write() -> generic_file_write() -> __alloc_pages() -> ...
- *
- * Same applies to ext3_get_block(). We will deadlock on various things like
- * lock_journal and i_truncate_mutex.
- *
- * Setting PF_MEMALLOC here doesn't work - too many internal memory
- * allocations fail.
- *
- * 16May01: If we're reentered then journal_current_handle() will be
- * non-zero. We simply *return*.
- *
- * 1 July 2001: @@@ FIXME:
- * In journalled data mode, a data buffer may be metadata against the
- * current transaction. But the same file is part of a shared mapping
- * and someone does a writepage() on it.
- *
- * We will move the buffer onto the async_data list, but *after* it has
- * been dirtied. So there's a small window where we have dirty data on
- * BJ_Metadata.
- *
- * Note that this only applies to the last partial page in the file. The
- * bit which block_write_full_page() uses prepare/commit for. (That's
- * broken code anyway: it's wrong for msync()).
- *
- * It's a rare case: affects the final partial page, for journalled data
- * where the file is subject to bith write() and writepage() in the same
- * transction. To fix it we'll need a custom block_write_full_page().
- * We'll probably need that anyway for journalling writepage() output.
- *
- * We don't honour synchronous mounts for writepage(). That would be
- * disastrous. Any write() or metadata operation will sync the fs for
- * us.
- *
- * AKPM2: if all the page's buffers are mapped to disk and !data=journal,
- * we don't need to open a transaction here.
- */
- static int ext3_ordered_writepage(struct page *page,
- struct writeback_control *wbc)
- {
- struct inode *inode = page->mapping->host;
- struct buffer_head *page_bufs;
- handle_t *handle = NULL;
- int ret = 0;
- int err;
- J_ASSERT(PageLocked(page));
- WARN_ON_ONCE(IS_RDONLY(inode));
- /*
- * We give up here if we're reentered, because it might be for a
- * different filesystem.
- */
- if (ext3_journal_current_handle())
- goto out_fail;
- trace_ext3_ordered_writepage(page);
- if (!page_has_buffers(page)) {
- create_empty_buffers(page, inode->i_sb->s_blocksize,
- (1 << BH_Dirty)|(1 << BH_Uptodate));
- page_bufs = page_buffers(page);
- } else {
- page_bufs = page_buffers(page);
- if (!walk_page_buffers(NULL, page_bufs, 0, PAGE_CACHE_SIZE,
- NULL, buffer_unmapped)) {
- /* Provide NULL get_block() to