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indirect.c
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/*
* linux/fs/ext4/indirect.c
*
* from
*
* linux/fs/ext4/inode.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card ([email protected])
* 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
* ([email protected]), 1993, 1998
*/
#include "ext4_jbd2.h"
#include "truncate.h"
#include <trace/events/ext4.h>
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;
}
/**
* ext4_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 ext4 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 ext4_block_to_path(struct inode *inode,
ext4_lblk_t i_block,
ext4_lblk_t offsets[4], int *boundary)
{
int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
const long direct_blocks = EXT4_NDIR_BLOCKS,
indirect_blocks = ptrs,
double_blocks = (1 << (ptrs_bits * 2));
int n = 0;
int final = 0;
if (i_block < direct_blocks) {
offsets[n++] = i_block;
final = direct_blocks;
} else if ((i_block -= direct_blocks) < indirect_blocks) {
offsets[n++] = EXT4_IND_BLOCK;
offsets[n++] = i_block;
final = ptrs;
} else if ((i_block -= indirect_blocks) < double_blocks) {
offsets[n++] = EXT4_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++] = EXT4_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 {
ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
i_block + direct_blocks +
indirect_blocks + double_blocks, inode->i_ino);
}
if (boundary)
*boundary = final - 1 - (i_block & (ptrs - 1));
return n;
}
/**
* ext4_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 reads all @depth-1 indirect blocks successfully and finds
* the whole chain, all way to the data (returns %NULL, *err == 0).
*
* Need to be called with
* down_read(&EXT4_I(inode)->i_data_sem)
*/
static Indirect *ext4_get_branch(struct inode *inode, int depth,
ext4_lblk_t *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, EXT4_I(inode)->i_data + *offsets);
if (!p->key)
goto no_block;
while (--depth) {
bh = sb_getblk(sb, le32_to_cpu(p->key));
if (unlikely(!bh))
goto failure;
if (!bh_uptodate_or_lock(bh)) {
if (bh_submit_read(bh) < 0) {
put_bh(bh);
goto failure;
}
/* validate block references */
if (ext4_check_indirect_blockref(inode, bh)) {
put_bh(bh);
goto failure;
}
}
add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
/* Reader: end */
if (!p->key)
goto no_block;
}
return NULL;
failure:
*err = -EIO;
no_block:
return p;
}
/**
* ext4_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 ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
{
struct ext4_inode_info *ei = EXT4_I(inode);
__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
__le32 *p;
/* 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.
*/
return ext4_inode_to_goal_block(inode);
}
/**
* ext4_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.
* Because this is only used for non-extent files, we limit the block nr
* to 32 bits.
*/
static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
Indirect *partial)
{
ext4_fsblk_t goal;
/*
* XXX need to get goal block from mballoc's data structures
*/
goal = ext4_find_near(inode, partial);
goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
return goal;
}
/**
* ext4_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 ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
int blocks_to_boundary)
{
unsigned int 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;
}
/**
* ext4_alloc_blocks: multiple allocate blocks needed for a branch
* @handle: handle for this transaction
* @inode: inode which needs allocated blocks
* @iblock: the logical block to start allocated at
* @goal: preferred physical block of allocation
* @indirect_blks: the number of blocks need to allocate for indirect
* blocks
* @blks: number of desired blocks
* @new_blocks: on return it will store the new block numbers for
* the indirect blocks(if needed) and the first direct block,
* @err: on return it will store the error code
*
* This function will return the number of blocks allocated as
* requested by the passed-in parameters.
*/
static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, ext4_fsblk_t goal,
int indirect_blks, int blks,
ext4_fsblk_t new_blocks[4], int *err)
{
struct ext4_allocation_request ar;
int target, i;
unsigned long count = 0, blk_allocated = 0;
int index = 0;
ext4_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)
*/
/* first we try to allocate the indirect blocks */
target = indirect_blks;
while (target > 0) {
count = target;
/* allocating blocks for indirect blocks and direct blocks */
current_block = ext4_new_meta_blocks(handle, inode, goal,
0, &count, err);
if (*err)
goto failed_out;
if (unlikely(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS)) {
EXT4_ERROR_INODE(inode,
"current_block %llu + count %lu > %d!",
current_block, count,
EXT4_MAX_BLOCK_FILE_PHYS);
*err = -EIO;
goto failed_out;
}
target -= count;
/* allocate blocks for indirect blocks */
while (index < indirect_blks && count) {
new_blocks[index++] = current_block++;
count--;
}
if (count > 0) {
/*
* save the new block number
* for the first direct block
*/
new_blocks[index] = current_block;
printk(KERN_INFO "%s returned more blocks than "
"requested\n", __func__);
WARN_ON(1);
break;
}
}
target = blks - count ;
blk_allocated = count;
if (!target)
goto allocated;
/* Now allocate data blocks */
memset(&ar, 0, sizeof(ar));
ar.inode = inode;
ar.goal = goal;
ar.len = target;
ar.logical = iblock;
if (S_ISREG(inode->i_mode))
/* enable in-core preallocation only for regular files */
ar.flags = EXT4_MB_HINT_DATA;
current_block = ext4_mb_new_blocks(handle, &ar, err);
if (unlikely(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS)) {
EXT4_ERROR_INODE(inode,
"current_block %llu + ar.len %d > %d!",
current_block, ar.len,
EXT4_MAX_BLOCK_FILE_PHYS);
*err = -EIO;
goto failed_out;
}
if (*err && (target == blks)) {
/*
* if the allocation failed and we didn't allocate
* any blocks before
*/
goto failed_out;
}
if (!*err) {
if (target == blks) {
/*
* save the new block number
* for the first direct block
*/
new_blocks[index] = current_block;
}
blk_allocated += ar.len;
}
allocated:
/* total number of blocks allocated for direct blocks */
ret = blk_allocated;
*err = 0;
return ret;
failed_out:
for (i = 0; i < index; i++)
ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
return ret;
}
/**
* ext4_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 ext4_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 ext4_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
* ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
* as described above and return 0.
*/
static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, int indirect_blks,
int *blks, ext4_fsblk_t goal,
ext4_lblk_t *offsets, Indirect *branch)
{
int blocksize = inode->i_sb->s_blocksize;
int i, n = 0;
int err = 0;
struct buffer_head *bh;
int num;
ext4_fsblk_t new_blocks[4];
ext4_fsblk_t current_block;
num = ext4_alloc_blocks(handle, inode, iblock, 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]);
if (unlikely(!bh)) {
err = -EIO;
goto failed;
}
branch[n].bh = bh;
lock_buffer(bh);
BUFFER_TRACE(bh, "call get_create_access");
err = ext4_journal_get_create_access(handle, bh);
if (err) {
/* Don't brelse(bh) here; it's done in
* ext4_journal_forget() below */
unlock_buffer(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 ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, inode, bh);
if (err)
goto failed;
}
*blks = num;
return err;
failed:
/* Allocation failed, free what we already allocated */
ext4_free_blocks(handle, inode, NULL, new_blocks[0], 1, 0);
for (i = 1; i <= n ; i++) {
/*
* branch[i].bh is newly allocated, so there is no
* need to revoke the block, which is why we don't
* need to set EXT4_FREE_BLOCKS_METADATA.
*/
ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1,
EXT4_FREE_BLOCKS_FORGET);
}
for (i = n+1; i < indirect_blks; i++)
ext4_free_blocks(handle, inode, NULL, new_blocks[i], 1, 0);
ext4_free_blocks(handle, inode, NULL, new_blocks[i], num, 0);
return err;
}
/**
* ext4_splice_branch - splice the allocated branch onto inode.
* @handle: handle for this transaction
* @inode: owner
* @block: (logical) number of block we are adding
* @chain: chain of indirect blocks (with a missing link - see
* ext4_alloc_branch)
* @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 ext4_splice_branch(handle_t *handle, struct inode *inode,
ext4_lblk_t block, Indirect *where, int num,
int blks)
{
int i;
int err = 0;
ext4_fsblk_t current_block;
/*
* 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 = ext4_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++);
}
/* We are done with atomic stuff, now do the rest of housekeeping */
/* 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->ext4_dirty_inode.
*/
jbd_debug(5, "splicing indirect only\n");
BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, inode, where->bh);
if (err)
goto err_out;
} else {
/*
* OK, we spliced it into the inode itself on a direct block.
*/
ext4_mark_inode_dirty(handle, inode);
jbd_debug(5, "splicing direct\n");
}
return err;
err_out:
for (i = 1; i <= num; i++) {
/*
* branch[i].bh is newly allocated, so there is no
* need to revoke the block, which is why we don't
* need to set EXT4_FREE_BLOCKS_METADATA.
*/
ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
EXT4_FREE_BLOCKS_FORGET);
}
ext4_free_blocks(handle, inode, NULL, le32_to_cpu(where[num].key),
blks, 0);
return err;
}
/*
* The ext4_ind_map_blocks() function handles non-extents inodes
* (i.e., using the traditional indirect/double-indirect i_blocks
* scheme) for ext4_map_blocks().
*
* 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.
*
* return > 0, # of blocks mapped or allocated.
* return = 0, if plain lookup failed.
* return < 0, error case.
*
* The ext4_ind_get_blocks() function should be called with
* down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
* blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
* down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
* blocks.
*/
int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
struct ext4_map_blocks *map,
int flags)
{
int err = -EIO;
ext4_lblk_t offsets[4];
Indirect chain[4];
Indirect *partial;
ext4_fsblk_t goal;
int indirect_blks;
int blocks_to_boundary = 0;
int depth;
int count = 0;
ext4_fsblk_t first_block = 0;
trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
depth = ext4_block_to_path(inode, map->m_lblk, offsets,
&blocks_to_boundary);
if (depth == 0)
goto out;
partial = ext4_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);
count++;
/*map more blocks*/
while (count < map->m_len && count <= blocks_to_boundary) {
ext4_fsblk_t blk;
blk = le32_to_cpu(*(chain[depth-1].p + count));
if (blk == first_block + count)
count++;
else
break;
}
goto got_it;
}
/* Next simple case - plain lookup or failed read of indirect block */
if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
goto cleanup;
/*
* Okay, we need to do block allocation.
*/
if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
EXT4_ERROR_INODE(inode, "Can't allocate blocks for "
"non-extent mapped inodes with bigalloc");
return -ENOSPC;
}
goal = ext4_find_goal(inode, map->m_lblk, 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 = ext4_blks_to_allocate(partial, indirect_blks,
map->m_len, blocks_to_boundary);
/*
* Block out ext4_truncate while we alter the tree
*/
err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
&count, goal,
offsets + (partial - chain), partial);
/*
* The ext4_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 = ext4_splice_branch(handle, inode, map->m_lblk,
partial, indirect_blks, count);
if (err)
goto cleanup;
map->m_flags |= EXT4_MAP_NEW;
ext4_update_inode_fsync_trans(handle, inode, 1);
got_it:
map->m_flags |= EXT4_MAP_MAPPED;
map->m_pblk = le32_to_cpu(chain[depth-1].key);
map->m_len = count;
if (count > blocks_to_boundary)
map->m_flags |= EXT4_MAP_BOUNDARY;
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--;
}
out:
trace_ext4_ind_map_blocks_exit(inode, map->m_lblk,
map->m_pblk, map->m_len, err);
return err;
}
/*
* O_DIRECT for ext3 (or indirect map) based files
*
* If the O_DIRECT write will extend the file then add this inode to the
* orphan list. So recovery will truncate it back to the original size
* if the machine crashes during the write.
*
* If the O_DIRECT write is intantiating holes inside i_size and the machine
* crashes then stale disk data _may_ be exposed inside the file. But current
* VFS code falls back into buffered path in that case so we are safe.
*/
ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct ext4_inode_info *ei = EXT4_I(inode);
handle_t *handle;
ssize_t ret;
int orphan = 0;
size_t count = iov_length(iov, nr_segs);
int retries = 0;
if (rw == WRITE) {
loff_t final_size = offset + count;
if (final_size > inode->i_size) {
/* Credits for sb + inode write */
handle = ext4_journal_start(inode, 2);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
goto out;
}
ret = ext4_orphan_add(handle, inode);
if (ret) {
ext4_journal_stop(handle);
goto out;
}
orphan = 1;
ei->i_disksize = inode->i_size;
ext4_journal_stop(handle);
}
}
retry:
if (rw == READ && ext4_should_dioread_nolock(inode)) {
if (unlikely(!list_empty(&ei->i_completed_io_list))) {
mutex_lock(&inode->i_mutex);
ext4_flush_completed_IO(inode);
mutex_unlock(&inode->i_mutex);
}
ret = __blockdev_direct_IO(rw, iocb, inode,
inode->i_sb->s_bdev, iov,
offset, nr_segs,
ext4_get_block, NULL, NULL, 0);
} else {
ret = blockdev_direct_IO(rw, iocb, inode, iov,
offset, nr_segs, ext4_get_block);
if (unlikely((rw & WRITE) && ret < 0)) {
loff_t isize = i_size_read(inode);
loff_t end = offset + iov_length(iov, nr_segs);
if (end > isize)
ext4_truncate_failed_write(inode);
}
}
if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
if (orphan) {
int err;
/* Credits for sb + inode write */
handle = ext4_journal_start(inode, 2);
if (IS_ERR(handle)) {
/* This is really bad luck. We've written the data
* but cannot extend i_size. Bail out and pretend
* the write failed... */
ret = PTR_ERR(handle);
if (inode->i_nlink)
ext4_orphan_del(NULL, inode);
goto out;
}
if (inode->i_nlink)
ext4_orphan_del(handle, inode);
if (ret > 0) {
loff_t end = offset + ret;
if (end > inode->i_size) {
ei->i_disksize = end;
i_size_write(inode, end);
/*
* We're going to return a positive `ret'
* here due to non-zero-length I/O, so there's
* no way of reporting error returns from
* ext4_mark_inode_dirty() to userspace. So
* ignore it.
*/
ext4_mark_inode_dirty(handle, inode);
}
}
err = ext4_journal_stop(handle);
if (ret == 0)
ret = err;
}
out:
return ret;
}
/*
* Calculate the number of metadata blocks need to reserve
* to allocate a new block at @lblocks for non extent file based file
*/
int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock)
{
struct ext4_inode_info *ei = EXT4_I(inode);
sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
int blk_bits;
if (lblock < EXT4_NDIR_BLOCKS)
return 0;
lblock -= EXT4_NDIR_BLOCKS;
if (ei->i_da_metadata_calc_len &&
(lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
ei->i_da_metadata_calc_len++;
return 0;
}
ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
ei->i_da_metadata_calc_len = 1;
blk_bits = order_base_2(lblock);
return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
}
int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk)
{
int indirects;
/* if nrblocks are contiguous */
if (chunk) {
/*
* With N contiguous data blocks, we need at most
* N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
* 2 dindirect blocks, and 1 tindirect block
*/
return DIV_ROUND_UP(nrblocks,
EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
}
/*
* if nrblocks are not contiguous, worse case, each block touch
* a indirect block, and each indirect block touch a double indirect
* block, plus a triple indirect block
*/
indirects = nrblocks * 2 + 1;
return indirects;
}
/*
* 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 = ext4_journal_start(inode, ext4_blocks_for_truncate(inode));
if (!IS_ERR(result))
return result;
ext4_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 (!ext4_handle_valid(handle))
return 0;
if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
return 0;
if (!ext4_journal_extend(handle, ext4_blocks_for_truncate(inode)))
return 0;
return 1;
}
/*
* Probably it should be a library function... search for first non-zero word
* or memcmp with zero_page, whatever is better for particular architecture.
* Linus?
*/
static inline int all_zeroes(__le32 *p, __le32 *q)
{
while (p < q)
if (*p++)
return 0;
return 1;
}
/**
* ext4_find_shared - find the indirect blocks for partial truncation.
* @inode: inode in question
* @depth: depth of the affected branch
* @offsets: offsets of pointers in that branch (see ext4_block_to_path)
* @chain: place to store the pointers to partial indirect blocks
* @top: place to the (detached) top of branch
*
* This is a helper function used by ext4_truncate().
*
* When we do truncate() we may have to clean the ends of several
* indirect blocks but leave the blocks themselves alive. Block is
* partially truncated if some data below the new i_size is referred
* from it (and it is on the path to the first completely truncated
* data block, indeed). We have to free the top of that path along
* with everything to the right of the path. Since no allocation
* past the truncation point is possible until ext4_truncate()
* finishes, we may safely do the latter, but top of branch may
* require special attention - pageout below the truncation point
* might try to populate it.
*
* We atomically detach the top of branch from the tree, store the
* block number of its root in *@top, pointers to buffer_heads of
* partially truncated blocks - in @chain[].bh and pointers to
* their last elements that should not be removed - in
* @chain[].p. Return value is the pointer to last filled element