Do not race for the lock of an inode hash.
Reviewed by: jhb
This commit is contained in:
parent
21cd6e6232
commit
937c4dfa08
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=69974
@ -1012,6 +1012,22 @@ ffs_sync(mp, waitfor, cred, p)
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* done by the calling routine.
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*/
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static int ffs_inode_hash_lock;
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/*
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* ffs_inode_hash_lock is a variable to manage mutual exclusion
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* of vnode allocation and intertion to the hash, especially to
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* avoid holding more than one vnodes for the same inode in the
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* hash table. ffs_inode_hash_lock must hence be tested-and-set
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* or cleared atomically, accomplished by ffs_inode_hash_mtx.
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*
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* As vnode allocation may block during MALLOC() and zone
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* allocation, we should also do msleep() to give away the CPU
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* if anyone else is allocating a vnode. lockmgr is not suitable
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* here because someone else may insert to the hash table the
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* vnode we are trying to allocate during our sleep, in which
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* case the hash table needs to be examined once again after
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* waking up.
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*/
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static struct mtx ffs_inode_hash_mtx;
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int
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ffs_vget(mp, ino, vpp)
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@ -1025,7 +1041,7 @@ ffs_vget(mp, ino, vpp)
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struct buf *bp;
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struct vnode *vp;
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dev_t dev;
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int error;
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int error, want_wakeup;
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ump = VFSTOUFS(mp);
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dev = ump->um_dev;
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@ -1039,14 +1055,17 @@ ffs_vget(mp, ino, vpp)
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* case getnewvnode() or MALLOC() blocks, otherwise a duplicate
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* may occur!
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*/
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mtx_enter(&ffs_inode_hash_mtx, MTX_DEF);
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if (ffs_inode_hash_lock) {
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while (ffs_inode_hash_lock) {
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ffs_inode_hash_lock = -1;
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tsleep(&ffs_inode_hash_lock, PVM, "ffsvgt", 0);
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msleep(&ffs_inode_hash_lock, &ffs_inode_hash_mtx, PVM, "ffsvgt", 0);
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}
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mtx_exit(&ffs_inode_hash_mtx, MTX_DEF);
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goto restart;
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}
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ffs_inode_hash_lock = 1;
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mtx_exit(&ffs_inode_hash_mtx, MTX_DEF);
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/*
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* If this MALLOC() is performed after the getnewvnode()
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@ -1061,9 +1080,17 @@ ffs_vget(mp, ino, vpp)
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/* Allocate a new vnode/inode. */
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error = getnewvnode(VT_UFS, mp, ffs_vnodeop_p, &vp);
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if (error) {
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if (ffs_inode_hash_lock < 0)
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wakeup(&ffs_inode_hash_lock);
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/*
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* Do not wake up processes while holding the mutex,
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* otherwise the processes waken up immediately hit
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* themselves into the mutex.
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*/
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mtx_enter(&ffs_inode_hash_mtx, MTX_DEF);
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want_wakeup = ffs_inode_hash_lock < 0;
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ffs_inode_hash_lock = 0;
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mtx_exit(&ffs_inode_hash_mtx, MTX_DEF);
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if (want_wakeup)
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wakeup(&ffs_inode_hash_lock);
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*vpp = NULL;
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FREE(ip, ump->um_malloctype);
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return (error);
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@ -1094,9 +1121,17 @@ ffs_vget(mp, ino, vpp)
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*/
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ufs_ihashins(ip);
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if (ffs_inode_hash_lock < 0)
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wakeup(&ffs_inode_hash_lock);
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/*
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* Do not wake up processes while holding the mutex,
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* otherwise the processes waken up immediately hit
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* themselves into the mutex.
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*/
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mtx_enter(&ffs_inode_hash_mtx, MTX_DEF);
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want_wakeup = ffs_inode_hash_lock < 0;
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ffs_inode_hash_lock = 0;
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mtx_exit(&ffs_inode_hash_mtx, MTX_DEF);
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if (want_wakeup)
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wakeup(&ffs_inode_hash_lock);
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/* Read in the disk contents for the inode, copy into the inode. */
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error = bread(ump->um_devvp, fsbtodb(fs, ino_to_fsba(fs, ino)),
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@ -1213,6 +1248,7 @@ ffs_init(vfsp)
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{
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softdep_initialize();
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mtx_init(&ffs_inode_hash_mtx, "ifsvgt", MTX_DEF);
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return (ufs_init(vfsp));
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}
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@ -101,6 +101,7 @@ static int
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ifs_init(vfsp)
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struct vfsconf *vfsp;
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{
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mtx_init(&ifs_inode_hash_mtx, "ifsvgt", MTX_DEF);
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return (ufs_init(vfsp));
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}
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@ -132,6 +133,22 @@ ifs_mount(mp, path, data, ndp, p)
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* done by the calling routine.
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*/
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static int ifs_inode_hash_lock;
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/*
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* ifs_inode_hash_lock is a variable to manage mutual exclusion
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* of vnode allocation and intertion to the hash, especially to
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* avoid holding more than one vnodes for the same inode in the
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* hash table. ifs_inode_hash_lock must hence be tested-and-set
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* or cleared atomically, accomplished by ifs_inode_hash_mtx.
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*
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* As vnode allocation may block during MALLOC() and zone
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* allocation, we should also do msleep() to give away the CPU
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* if anyone else is allocating a vnode. lockmgr is not suitable
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* here because someone else may insert to the hash table the
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* vnode we are trying to allocate during our sleep, in which
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* case the hash table needs to be examined once again after
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* waking up.
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*/
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static struct mtx ifs_inode_hash_mtx;
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int
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ifs_vget(mp, ino, vpp)
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@ -145,7 +162,7 @@ ifs_vget(mp, ino, vpp)
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struct buf *bp;
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struct vnode *vp;
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dev_t dev;
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int error;
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int error, want_wakeup;
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ump = VFSTOUFS(mp);
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dev = ump->um_dev;
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@ -159,14 +176,17 @@ ifs_vget(mp, ino, vpp)
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* case getnewvnode() or MALLOC() blocks, otherwise a duplicate
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* may occur!
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*/
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mtx_enter(&ifs_inode_hash_mtx, MTX_DEF);
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if (ifs_inode_hash_lock) {
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while (ifs_inode_hash_lock) {
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ifs_inode_hash_lock = -1;
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tsleep(&ifs_inode_hash_lock, PVM, "ifsvgt", 0);
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msleep(&ifs_inode_hash_lock, &ifs_inode_hash_mtx, PVM, "ifsvgt", 0);
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}
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mtx_exit(&ifs_inode_hash_mtx, MTX_DEF);
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goto restart;
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}
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ifs_inode_hash_lock = 1;
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mtx_exit(&ifs_inode_hash_mtx, MTX_DEF);
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/*
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* If this MALLOC() is performed after the getnewvnode()
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@ -181,9 +201,17 @@ ifs_vget(mp, ino, vpp)
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/* Allocate a new vnode/inode. */
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error = getnewvnode(VT_UFS, mp, ifs_vnodeop_p, &vp);
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if (error) {
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if (ifs_inode_hash_lock < 0)
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wakeup(&ifs_inode_hash_lock);
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/*
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* Do not wake up processes while holding the mutex,
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* otherwise the processes waken up immediately hit
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* themselves into the mutex.
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*/
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mtx_enter(&ifs_inode_hash_mtx, MTX_DEF);
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want_wakeup = ifs_inode_hash_lock < 0;
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ifs_inode_hash_lock = 0;
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mtx_exit(&ifs_inode_hash_mtx, MTX_DEF);
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if (want_wakeup)
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wakeup(&ifs_inode_hash_lock);
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*vpp = NULL;
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FREE(ip, ump->um_malloctype);
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return (error);
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@ -214,9 +242,17 @@ ifs_vget(mp, ino, vpp)
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*/
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ufs_ihashins(ip);
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if (ifs_inode_hash_lock < 0)
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wakeup(&ifs_inode_hash_lock);
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/*
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* Do not wake up processes while holding the mutex,
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* otherwise the processes waken up immediately hit
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* themselves into the mutex.
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*/
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mtx_enter(&ifs_inode_hash_mtx, MTX_DEF);
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want_wakeup = ffs_inode_hash_lock < 0;
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ifs_inode_hash_lock = 0;
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mtx_exit(&ifs_inode_hash_mtx, MTX_DEF);
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if (want_wakeup)
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wakeup(&ifs_inode_hash_lock);
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/* Read in the disk contents for the inode, copy into the inode. */
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error = bread(ump->um_devvp, fsbtodb(fs, ino_to_fsba(fs, ino)),
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