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[XFS] revert to double-buffering readdir

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The current readdir implementation deadlocks on a btree buffers locks
because nfsd calls back into ->lookup from the filldir callback. The only
short-term fix for this is to revert to the old inefficient
double-buffering scheme.

SGI-PV: 973377
SGI-Modid: xfs-linux-melb:xfs-kern:30201a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
This commit is contained in:
Christoph Hellwig 2007-12-07 14:07:53 +11:00 committed by Lachlan McIlroy
parent a7430847fc
commit e89bc612d6
1 changed files with 124 additions and 0 deletions
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124
fs/xfs/linux-2.6/xfs_file.c
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@ -218,6 +218,15 @@ xfs_vm_fault(
}
#endif /* CONFIG_XFS_DMAPI */
/*
* Unfortunately we can't just use the clean and simple readdir implementation
* below, because nfs might call back into ->lookup from the filldir callback
* and that will deadlock the low-level btree code.
*
* Hopefully we'll find a better workaround that allows to use the optimal
* version at least for local readdirs for 2.6.25.
*/
#if 0
STATIC int
xfs_file_readdir(
struct file *filp,
@ -249,6 +258,121 @@ xfs_file_readdir(
return -error;
return 0;
}
#else
struct hack_dirent {
int namlen;
loff_t offset;
u64 ino;
unsigned int d_type;
char name[];
};
struct hack_callback {
char *dirent;
size_t len;
size_t used;
};
STATIC int
xfs_hack_filldir(
void *__buf,
const char *name,
int namlen,
loff_t offset,
u64 ino,
unsigned int d_type)
{
struct hack_callback *buf = __buf;
struct hack_dirent *de = (struct hack_dirent *)(buf->dirent + buf->used);
if (buf->used + sizeof(struct hack_dirent) + namlen > buf->len)
return -EINVAL;
de->namlen = namlen;
de->offset = offset;
de->ino = ino;
de->d_type = d_type;
memcpy(de->name, name, namlen);
buf->used += sizeof(struct hack_dirent) + namlen;
return 0;
}
STATIC int
xfs_file_readdir(
struct file *filp,
void *dirent,
filldir_t filldir)
{
struct inode *inode = filp->f_path.dentry->d_inode;
xfs_inode_t *ip = XFS_I(inode);
struct hack_callback buf;
struct hack_dirent *de;
int error;
loff_t size;
int eof = 0;
xfs_off_t start_offset, curr_offset, offset;
/*
* Try fairly hard to get memory
*/
buf.len = PAGE_CACHE_SIZE;
do {
buf.dirent = kmalloc(buf.len, GFP_KERNEL);
if (buf.dirent)
break;
buf.len >>= 1;
} while (buf.len >= 1024);
if (!buf.dirent)
return -ENOMEM;
curr_offset = filp->f_pos;
if (curr_offset == 0x7fffffff)
offset = 0xffffffff;
else
offset = filp->f_pos;
while (!eof) {
int reclen;
start_offset = offset;
buf.used = 0;
error = -xfs_readdir(ip, &buf, buf.len, &offset,
xfs_hack_filldir);
if (error || offset == start_offset) {
size = 0;
break;
}
size = buf.used;
de = (struct hack_dirent *)buf.dirent;
while (size > 0) {
if (filldir(dirent, de->name, de->namlen,
curr_offset & 0x7fffffff,
de->ino, de->d_type)) {
goto done;
}
reclen = sizeof(struct hack_dirent) + de->namlen;
size -= reclen;
curr_offset = de->offset /* & 0x7fffffff */;
de = (struct hack_dirent *)((char *)de + reclen);
}
}
done:
if (!error) {
if (size == 0)
filp->f_pos = offset & 0x7fffffff;
else if (de)
filp->f_pos = curr_offset;
}
kfree(buf.dirent);
return error;
}
#endif
STATIC int
xfs_file_mmap(