[XFS] factor xfs_iget_core() into hit and miss cases
There are really two cases in xfs_iget_core(). The first is the cache hit case, the second is the miss case. They share very little code, and hence can easily be factored out into separate functions. This makes the code much easier to understand and subsequently modify. SGI-PV: 988141 SGI-Modid: xfs-linux-melb:xfs-kern:32317a Signed-off-by: David Chinner <david@fromorbit.com> Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
This commit is contained in:
David Chinner
Lachlan McIlroy
parent
3471394ba5
commit
6441e54915
@ -39,6 +39,179 @@
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#include "xfs_quota.h"
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#include "xfs_utils.h"
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/*
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* Check the validity of the inode we just found it the cache
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*/
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static int
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xfs_iget_cache_hit(
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struct inode *inode,
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struct xfs_perag *pag,
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struct xfs_inode *ip,
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int flags,
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int lock_flags) __releases(pag->pag_ici_lock)
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{
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struct xfs_mount *mp = ip->i_mount;
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struct inode *old_inode;
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int error = 0;
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/*
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* If INEW is set this inode is being set up
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* Pause and try again.
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*/
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if (xfs_iflags_test(ip, XFS_INEW)) {
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error = EAGAIN;
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XFS_STATS_INC(xs_ig_frecycle);
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goto out_error;
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}
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old_inode = ip->i_vnode;
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if (old_inode == NULL) {
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/*
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* If IRECLAIM is set this inode is
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* on its way out of the system,
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* we need to pause and try again.
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*/
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if (xfs_iflags_test(ip, XFS_IRECLAIM)) {
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error = EAGAIN;
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XFS_STATS_INC(xs_ig_frecycle);
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goto out_error;
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}
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ASSERT(xfs_iflags_test(ip, XFS_IRECLAIMABLE));
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/*
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* If lookup is racing with unlink, then we
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* should return an error immediately so we
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* don't remove it from the reclaim list and
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* potentially leak the inode.
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*/
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if ((ip->i_d.di_mode == 0) &&
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!(flags & XFS_IGET_CREATE)) {
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error = ENOENT;
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goto out_error;
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}
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xfs_itrace_exit_tag(ip, "xfs_iget.alloc");
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xfs_iflags_clear(ip, XFS_IRECLAIMABLE);
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read_unlock(&pag->pag_ici_lock);
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XFS_MOUNT_ILOCK(mp);
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list_del_init(&ip->i_reclaim);
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XFS_MOUNT_IUNLOCK(mp);
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} else if (inode != old_inode) {
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/* The inode is being torn down, pause and
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* try again.
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*/
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if (old_inode->i_state & (I_FREEING | I_CLEAR)) {
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error = EAGAIN;
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XFS_STATS_INC(xs_ig_frecycle);
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goto out_error;
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}
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/* Chances are the other vnode (the one in the inode) is being torn
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* down right now, and we landed on top of it. Question is, what do
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* we do? Unhook the old inode and hook up the new one?
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*/
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cmn_err(CE_PANIC,
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"xfs_iget_core: ambiguous vns: vp/0x%p, invp/0x%p",
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old_inode, inode);
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} else {
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read_unlock(&pag->pag_ici_lock);
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}
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if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
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error = ENOENT;
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goto out;
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}
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if (lock_flags != 0)
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xfs_ilock(ip, lock_flags);
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xfs_iflags_clear(ip, XFS_ISTALE);
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xfs_itrace_exit_tag(ip, "xfs_iget.found");
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XFS_STATS_INC(xs_ig_found);
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return 0;
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out_error:
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read_unlock(&pag->pag_ici_lock);
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out:
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return error;
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}
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static int
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xfs_iget_cache_miss(
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struct xfs_mount *mp,
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struct xfs_perag *pag,
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xfs_trans_t *tp,
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xfs_ino_t ino,
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struct xfs_inode **ipp,
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xfs_daddr_t bno,
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int flags,
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int lock_flags) __releases(pag->pag_ici_lock)
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{
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struct xfs_inode *ip;
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int error;
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unsigned long first_index, mask;
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xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ino);
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/*
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* Read the disk inode attributes into a new inode structure and get
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* a new vnode for it. This should also initialize i_ino and i_mount.
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*/
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error = xfs_iread(mp, tp, ino, &ip, bno,
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(flags & XFS_IGET_BULKSTAT) ? XFS_IMAP_BULKSTAT : 0);
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if (error)
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return error;
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xfs_itrace_exit_tag(ip, "xfs_iget.alloc");
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if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
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error = ENOENT;
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goto out_destroy;
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}
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/*
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* Preload the radix tree so we can insert safely under the
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* write spinlock.
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*/
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if (radix_tree_preload(GFP_KERNEL)) {
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error = EAGAIN;
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goto out_destroy;
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}
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if (lock_flags)
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xfs_ilock(ip, lock_flags);
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mask = ~(((XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog)) - 1);
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first_index = agino & mask;
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write_lock(&pag->pag_ici_lock);
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/* insert the new inode */
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error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
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if (unlikely(error)) {
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WARN_ON(error != -EEXIST);
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XFS_STATS_INC(xs_ig_dup);
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error = EAGAIN;
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goto out_unlock;
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}
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/* These values _must_ be set before releasing the radix tree lock! */
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ip->i_udquot = ip->i_gdquot = NULL;
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xfs_iflags_set(ip, XFS_INEW);
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write_unlock(&pag->pag_ici_lock);
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radix_tree_preload_end();
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*ipp = ip;
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return 0;
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out_unlock:
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write_unlock(&pag->pag_ici_lock);
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radix_tree_preload_end();
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out_destroy:
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xfs_idestroy(ip);
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return error;
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}
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/*
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* Look up an inode by number in the given file system.
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* The inode is looked up in the cache held in each AG.
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@ -74,10 +247,8 @@ xfs_iget_core(
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xfs_inode_t **ipp,
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xfs_daddr_t bno)
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{
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struct inode *old_inode;
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xfs_inode_t *ip;
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int error;
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unsigned long first_index, mask;
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xfs_perag_t *pag;
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xfs_agino_t agino;
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@ -93,170 +264,25 @@ xfs_iget_core(
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agino = XFS_INO_TO_AGINO(mp, ino);
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again:
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error = 0;
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read_lock(&pag->pag_ici_lock);
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ip = radix_tree_lookup(&pag->pag_ici_root, agino);
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if (ip != NULL) {
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/*
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* If INEW is set this inode is being set up
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* we need to pause and try again.
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*/
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if (xfs_iflags_test(ip, XFS_INEW)) {
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read_unlock(&pag->pag_ici_lock);
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delay(1);
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XFS_STATS_INC(xs_ig_frecycle);
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goto again;
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}
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old_inode = ip->i_vnode;
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if (old_inode == NULL) {
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/*
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* If IRECLAIM is set this inode is
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* on its way out of the system,
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* we need to pause and try again.
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*/
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if (xfs_iflags_test(ip, XFS_IRECLAIM)) {
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read_unlock(&pag->pag_ici_lock);
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delay(1);
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XFS_STATS_INC(xs_ig_frecycle);
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goto again;
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}
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ASSERT(xfs_iflags_test(ip, XFS_IRECLAIMABLE));
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/*
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* If lookup is racing with unlink, then we
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* should return an error immediately so we
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* don't remove it from the reclaim list and
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* potentially leak the inode.
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*/
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if ((ip->i_d.di_mode == 0) &&
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!(flags & XFS_IGET_CREATE)) {
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read_unlock(&pag->pag_ici_lock);
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xfs_put_perag(mp, pag);
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return ENOENT;
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}
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xfs_itrace_exit_tag(ip, "xfs_iget.alloc");
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XFS_STATS_INC(xs_ig_found);
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xfs_iflags_clear(ip, XFS_IRECLAIMABLE);
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read_unlock(&pag->pag_ici_lock);
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XFS_MOUNT_ILOCK(mp);
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list_del_init(&ip->i_reclaim);
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XFS_MOUNT_IUNLOCK(mp);
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goto finish_inode;
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} else if (inode != old_inode) {
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/* The inode is being torn down, pause and
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* try again.
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*/
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if (old_inode->i_state & (I_FREEING | I_CLEAR)) {
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read_unlock(&pag->pag_ici_lock);
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delay(1);
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XFS_STATS_INC(xs_ig_frecycle);
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goto again;
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}
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/* Chances are the other vnode (the one in the inode) is being torn
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* down right now, and we landed on top of it. Question is, what do
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* we do? Unhook the old inode and hook up the new one?
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*/
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cmn_err(CE_PANIC,
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"xfs_iget_core: ambiguous vns: vp/0x%p, invp/0x%p",
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old_inode, inode);
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}
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/*
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* Inode cache hit
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*/
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if (ip) {
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error = xfs_iget_cache_hit(inode, pag, ip, flags, lock_flags);
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if (error)
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goto out_error_or_again;
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} else {
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read_unlock(&pag->pag_ici_lock);
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XFS_STATS_INC(xs_ig_found);
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XFS_STATS_INC(xs_ig_missed);
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finish_inode:
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if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
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xfs_put_perag(mp, pag);
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return ENOENT;
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}
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if (lock_flags != 0)
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xfs_ilock(ip, lock_flags);
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xfs_iflags_clear(ip, XFS_ISTALE);
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xfs_itrace_exit_tag(ip, "xfs_iget.found");
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goto return_ip;
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error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip, bno,
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flags, lock_flags);
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if (error)
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goto out_error_or_again;
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}
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/*
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* Inode cache miss
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*/
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read_unlock(&pag->pag_ici_lock);
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XFS_STATS_INC(xs_ig_missed);
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/*
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* Read the disk inode attributes into a new inode structure and get
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* a new vnode for it. This should also initialize i_ino and i_mount.
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*/
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error = xfs_iread(mp, tp, ino, &ip, bno,
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(flags & XFS_IGET_BULKSTAT) ? XFS_IMAP_BULKSTAT : 0);
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if (error) {
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xfs_put_perag(mp, pag);
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return error;
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}
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xfs_itrace_exit_tag(ip, "xfs_iget.alloc");
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if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
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xfs_idestroy(ip);
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xfs_put_perag(mp, pag);
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return ENOENT;
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}
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/*
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* Preload the radix tree so we can insert safely under the
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* write spinlock.
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*/
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if (radix_tree_preload(GFP_KERNEL)) {
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xfs_idestroy(ip);
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delay(1);
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goto again;
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}
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if (lock_flags)
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xfs_ilock(ip, lock_flags);
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mask = ~(((XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog)) - 1);
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first_index = agino & mask;
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write_lock(&pag->pag_ici_lock);
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/*
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* insert the new inode
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*/
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error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
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if (unlikely(error)) {
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BUG_ON(error != -EEXIST);
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write_unlock(&pag->pag_ici_lock);
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radix_tree_preload_end();
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if (lock_flags)
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xfs_iunlock(ip, lock_flags);
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xfs_idestroy(ip);
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XFS_STATS_INC(xs_ig_dup);
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goto again;
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}
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/*
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* These values _must_ be set before releasing the radix tree lock!
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*/
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ip->i_udquot = ip->i_gdquot = NULL;
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xfs_iflags_set(ip, XFS_INEW);
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write_unlock(&pag->pag_ici_lock);
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radix_tree_preload_end();
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xfs_put_perag(mp, pag);
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return_ip:
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ASSERT(ip->i_df.if_ext_max ==
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XFS_IFORK_DSIZE(ip) / sizeof(xfs_bmbt_rec_t));
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@ -276,6 +302,14 @@ xfs_iget_core(
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if (ip->i_d.di_mode != 0)
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xfs_setup_inode(ip);
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return 0;
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out_error_or_again:
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if (error == EAGAIN) {
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delay(1);
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goto again;
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}
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xfs_put_perag(mp, pag);
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return error;
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}
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