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Subject[CFT][PATCH] write() fixes.
	Folks, the patch below is a combination of -EFBIG fixes posted
yesterday with _very_ preliminary stuff that deals with behaviour of
write() in cases when get_block() fails. It compiles, but that's about
all I can really promise.
Please, give it a try. It should be reasonably safe (pathes
affected by the untested stuff are in error-handling). Things to test
for: behaviour of write() when disk gets full (just mount a floppy with
ext2 and play with it - that way the rest of filesystems is unlikely
to be eaten). Specifically, try writing to the file in big chunks
and look at the results of partial write (when disk gets full). Then
unmount fs and mount it again, expand the file with truncate() and see
if the contents looks right - code currently in the tree sometimes leaves
a junk in the end (and makes fsck unhappy, BTW). Ditto for writing into the
holes. If the things will look decent that goes to Linus and after
we-all-know-what I'm somewhat nervous about the changes affecting
__block_prepare_write(), generic_file_write() and vmtruncate()...

Cheers,
Al

diff -urN rc11-pre7/fs/buffer.c rc11-pre7-ext2/fs/buffer.c
--- rc11-pre7/fs/buffer.c Sat Nov 18 00:28:13 2000
+++ rc11-pre7-ext2/fs/buffer.c Sun Nov 19 05:34:20 2000
@@ -1527,6 +1527,15 @@
}
return 0;
out:
+ bh = head;
+ do {
+ if (buffer_new(bh) && !buffer_uptodate(bh)) {
+ memset(bh->b_data, 0, bh->b_size);
+ set_bit(BH_Uptodate, &bh->b_state);
+ mark_buffer_dirty(bh);
+ }
+ bh = bh->b_this_page;
+ } while (bh != head);
return err;
}

diff -urN rc11-pre7/fs/ext2/file.c rc11-pre7-ext2/fs/ext2/file.c
--- rc11-pre7/fs/ext2/file.c Wed Oct 4 03:44:54 2000
+++ rc11-pre7-ext2/fs/ext2/file.c Sun Nov 19 05:22:25 2000
@@ -25,17 +25,6 @@
static loff_t ext2_file_lseek(struct file *, loff_t, int);
static int ext2_open_file (struct inode *, struct file *);

-#define EXT2_MAX_SIZE(bits) \
- (((EXT2_NDIR_BLOCKS + (1LL << (bits - 2)) + \
- (1LL << (bits - 2)) * (1LL << (bits - 2)) + \
- (1LL << (bits - 2)) * (1LL << (bits - 2)) * (1LL << (bits - 2))) * \
- (1LL << bits)) - 1)
-
-static long long ext2_max_sizes[] = {
-0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-EXT2_MAX_SIZE(10), EXT2_MAX_SIZE(11), EXT2_MAX_SIZE(12), EXT2_MAX_SIZE(13)
-};
-
/*
* Make sure the offset never goes beyond the 32-bit mark..
*/
@@ -56,7 +45,7 @@
if (offset<0)
return -EINVAL;
if (((unsigned long long) offset >> 32) != 0) {
- if (offset > ext2_max_sizes[EXT2_BLOCK_SIZE_BITS(inode->i_sb)])
+ if (offset >= inode->i_sb->u.ext2_sb.s_max_size)
return -EINVAL;
}
if (offset != file->f_pos) {
@@ -110,4 +99,5 @@

struct inode_operations ext2_file_inode_operations = {
truncate: ext2_truncate,
+ setattr: ext2_notify_change,
};
diff -urN rc11-pre7/fs/ext2/inode.c rc11-pre7-ext2/fs/ext2/inode.c
--- rc11-pre7/fs/ext2/inode.c Wed Oct 4 03:44:54 2000
+++ rc11-pre7-ext2/fs/ext2/inode.c Sun Nov 19 05:23:04 2000
@@ -153,11 +153,13 @@
* 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.
+ * (negative or too large) we return zero. Warning is printed if @block
+ * is negative - that should never happen. Too large value is OK, it
+ * just means that ext2_get_block() should return -%EFBIG.
*
* 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).
+ * @inode->i_sb).
*/

/*
@@ -196,7 +198,7 @@
offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
offsets[n++] = i_block & (ptrs - 1);
} else {
- ext2_warning (inode->i_sb, "ext2_block_to_path", "block > big");
+ /* Too large, nothing to do here */
}
return n;
}
@@ -216,7 +218,7 @@
* 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
+ * 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.
@@ -230,11 +232,11 @@
* 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 inline Indirect *ext2_get_branch(struct inode *inode,
- int depth,
- int *offsets,
- Indirect chain[4],
- int *err)
+static Indirect *ext2_get_branch(struct inode *inode,
+ int depth,
+ int *offsets,
+ Indirect chain[4],
+ int *err)
{
kdev_t dev = inode->i_dev;
int size = inode->i_sb->s_blocksize;
@@ -505,7 +507,7 @@

static int ext2_get_block(struct inode *inode, long iblock, struct buffer_head *bh_result, int create)
{
- int err = -EIO;
+ int err = -EFBIG;
int offsets[4];
Indirect chain[4];
Indirect *partial;
@@ -880,8 +882,6 @@
if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
S_ISLNK(inode->i_mode)))
return;
- if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
- return;

ext2_discard_prealloc(inode);

@@ -1255,6 +1255,13 @@
retval = inode_change_ok(inode, iattr);
if (retval != 0)
goto out;
+
+ if (iattr->ia_valid & ATTR_SIZE) {
+ if (iattr->ia_size > inode->i_sb->u.ext2_sb.s_max_size) {
+ retval = -EFBIG;
+ goto out;
+ }
+ }

inode_setattr(inode, iattr);

diff -urN rc11-pre7/fs/ext2/super.c rc11-pre7-ext2/fs/ext2/super.c
--- rc11-pre7/fs/ext2/super.c Wed Oct 4 03:44:54 2000
+++ rc11-pre7-ext2/fs/ext2/super.c Sun Nov 19 05:22:25 2000
@@ -356,6 +356,19 @@

#define log2(n) ffz(~(n))

+/*
+ * maximal file size.
+ */
+static loff_t ext2_max_size(int bits)
+{
+ loff_t res = EXT2_NDIR_BLOCKS;
+ res += 1LL << (bits-2);
+ res += 1LL << (2*(bits-2));
+ res += 1LL << (3*(bits-2));
+ return res << bits;
+}
+
+
struct super_block * ext2_read_super (struct super_block * sb, void * data,
int silent)
{
@@ -517,6 +530,7 @@
log2 (EXT2_ADDR_PER_BLOCK(sb));
sb->u.ext2_sb.s_desc_per_block_bits =
log2 (EXT2_DESC_PER_BLOCK(sb));
+ sb->u.ext2_sb.s_max_size = ext2_max_size(sb->s_blocksize_bits);
if (sb->s_magic != EXT2_SUPER_MAGIC) {
if (!silent)
printk ("VFS: Can't find an ext2 filesystem on dev "
diff -urN rc11-pre7/fs/nfsd/vfs.c rc11-pre7-ext2/fs/nfsd/vfs.c
--- rc11-pre7/fs/nfsd/vfs.c Sat Nov 18 00:28:17 2000
+++ rc11-pre7-ext2/fs/nfsd/vfs.c Sun Nov 19 05:22:25 2000
@@ -23,7 +23,6 @@
#include <linux/locks.h>
#include <linux/fs.h>
#include <linux/major.h>
-#include <linux/ext2_fs.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
diff -urN rc11-pre7/fs/open.c rc11-pre7-ext2/fs/open.c
--- rc11-pre7/fs/open.c Thu Nov 2 22:38:59 2000
+++ rc11-pre7-ext2/fs/open.c Sun Nov 19 05:22:25 2000
@@ -102,7 +102,12 @@
goto out;
inode = nd.dentry->d_inode;

- error = -EACCES;
+ /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
+ error = -EISDIR;
+ if (S_ISDIR(inode->i_mode))
+ goto dput_and_out;
+
+ error = -EINVAL;
if (!S_ISREG(inode->i_mode))
goto dput_and_out;

@@ -163,7 +168,7 @@
goto out;
dentry = file->f_dentry;
inode = dentry->d_inode;
- error = -EACCES;
+ error = -EINVAL;
if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
goto out_putf;
error = -EPERM;
diff -urN rc11-pre7/include/linux/ext2_fs.h rc11-pre7-ext2/include/linux/ext2_fs.h
--- rc11-pre7/include/linux/ext2_fs.h Sat Jul 29 12:08:57 2000
+++ rc11-pre7-ext2/include/linux/ext2_fs.h Sun Nov 19 05:22:25 2000
@@ -568,6 +568,8 @@
extern int ext2_sync_inode (struct inode *);
extern void ext2_discard_prealloc (struct inode *);

+extern int ext2_notify_change (struct dentry *, struct iattr *);
+
/* ioctl.c */
extern int ext2_ioctl (struct inode *, struct file *, unsigned int,
unsigned long);
diff -urN rc11-pre7/include/linux/ext2_fs_sb.h rc11-pre7-ext2/include/linux/ext2_fs_sb.h
--- rc11-pre7/include/linux/ext2_fs_sb.h Wed Oct 4 03:45:06 2000
+++ rc11-pre7-ext2/include/linux/ext2_fs_sb.h Sun Nov 19 05:22:25 2000
@@ -59,6 +59,7 @@
int s_feature_compat;
int s_feature_incompat;
int s_feature_ro_compat;
+ loff_t s_max_size;
};

#endif /* _LINUX_EXT2_FS_SB */
diff -urN rc11-pre7/kernel/ksyms.c rc11-pre7-ext2/kernel/ksyms.c
--- rc11-pre7/kernel/ksyms.c Sat Nov 18 00:28:25 2000
+++ rc11-pre7-ext2/kernel/ksyms.c Sun Nov 19 05:22:25 2000
@@ -23,8 +23,6 @@
#include <linux/serial.h>
#include <linux/locks.h>
#include <linux/delay.h>
-#include <linux/minix_fs.h>
-#include <linux/ext2_fs.h>
#include <linux/random.h>
#include <linux/reboot.h>
#include <linux/pagemap.h>
diff -urN rc11-pre7/mm/filemap.c rc11-pre7-ext2/mm/filemap.c
--- rc11-pre7/mm/filemap.c Sat Nov 18 00:28:25 2000
+++ rc11-pre7-ext2/mm/filemap.c Sun Nov 19 06:21:39 2000
@@ -2422,6 +2422,7 @@
unsigned long written;
long status;
int err;
+ unsigned bytes;

cached_page = NULL;

@@ -2466,7 +2467,7 @@
}

while (count) {
- unsigned long bytes, index, offset;
+ unsigned index, offset;
char *kaddr;

/*
@@ -2491,7 +2492,7 @@

status = mapping->a_ops->prepare_write(file, page, offset, offset+bytes);
if (status)
- goto unlock;
+ goto sync_failure;
kaddr = page_address(page);
status = copy_from_user(kaddr+offset, buf, bytes);
flush_dcache_page(page);
@@ -2516,6 +2517,7 @@
if (status < 0)
break;
}
+done:
*ppos = pos;

if (cached_page)
@@ -2530,6 +2532,13 @@
ClearPageUptodate(page);
kunmap(page);
goto unlock;
+sync_failure:
+ UnlockPage(page);
+ deactivate_page(page);
+ page_cache_release(page);
+ if (pos + bytes > inode->i_size)
+ vmtruncate(inode, inode->i_size);
+ goto done;
}

void __init page_cache_init(unsigned long mempages)
-
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