Techwizz/kernel-fxtec-pro1x
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

ceph: fix sync read eof check deadlock

Browse source 
If a sync read gets a short result from the OSD, it may need to do a
getattr to see if it is short due to reaching end-of-file.  The getattr
was being done while holding a reference to FILE_RD, which can lead to
a deadlock if the MDS is revoking that capability bit and can't process
the getattr until it does.

We fix this by setting a flag if EOF size validation is needed, and doing
the getattr in ceph_aio_read, after the RD cap ref is dropped.  If the
read needs to be continued, we loop and continue traversing the file.

Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2010-02-09 14:04:02 -08:00
parent 68c283236a
commit 6a026589ba
1 changed files with 26 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

39
fs/ceph/file.c
View file

@ -431,7 +431,8 @@ static void zero_page_vector_range(int off, int len, struct page **pages)
*/
static int striped_read(struct inode *inode,
u64 off, u64 len,
struct page **pages, int num_pages)
struct page **pages, int num_pages,
int *checkeof)
{
struct ceph_client *client = ceph_inode_to_client(inode);
struct ceph_inode_info *ci = ceph_inode(inode);
@ -497,15 +498,7 @@ static int striped_read(struct inode *inode,
}
/* check i_size */
ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
if (ret < 0)
goto out;
/* hit EOF? */
if (pos >= inode->i_size)
goto out;
goto more;
*checkeof = 1;
}
out:
@ -522,7 +515,7 @@ static int striped_read(struct inode *inode,
* If the read spans object boundary, just do multiple reads.
*/
static ssize_t ceph_sync_read(struct file *file, char __user *data,
unsigned len, loff_t *poff)
unsigned len, loff_t *poff, int *checkeof)
{
struct inode *inode = file->f_dentry->d_inode;
struct page **pages;
@ -552,7 +545,7 @@ static ssize_t ceph_sync_read(struct file *file, char __user *data,
if (ret < 0)
goto done;
ret = striped_read(inode, off, len, pages, num_pages);
ret = striped_read(inode, off, len, pages, num_pages, checkeof);
if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)
ret = copy_page_vector_to_user(pages, data, off, ret);
@ -746,11 +739,14 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
size_t len = iov->iov_len;
struct inode *inode = filp->f_dentry->d_inode;
struct ceph_inode_info *ci = ceph_inode(inode);
void *base = iov->iov_base;
ssize_t ret;
int got = 0;
int checkeof = 0, read = 0;
dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
inode, ceph_vinop(inode), pos, (unsigned)len, inode);
again:
__ceph_do_pending_vmtruncate(inode);
ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, CEPH_CAP_FILE_CACHE,
&got, -1);
@ -764,7 +760,7 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
(iocb->ki_filp->f_flags & O_DIRECT) ||
(inode->i_sb->s_flags & MS_SYNCHRONOUS))
/* hmm, this isn't really async... */
ret = ceph_sync_read(filp, iov->iov_base, len, ppos);
ret = ceph_sync_read(filp, base, len, ppos, &checkeof);
else
ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
@ -772,6 +768,23 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
ceph_put_cap_refs(ci, got);
if (checkeof && ret >= 0) {
int statret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
/* hit EOF or hole? */
if (statret == 0 && *ppos < inode->i_size) {
dout("aio_read sync_read hit hole, reading more\n");
read += ret;
base += ret;
len -= ret;
checkeof = 0;
goto again;
}
}
if (ret >= 0)
ret += read;
return ret;
}